Remove gists and fix iOS instructions

Summary:
Remove gists in code blocks. This also made it easier to fix the iOS sample app instructions in the getting started.

>Note: I also needed to update my gems as I was having problems running `bundle install`. The errors were around installing json v1.8.3. It was resolved by creating a new Gemfile.lock.

1. Build website and check changed pages (see attached Getting Started for an example)
2. Also check how it would look for mobile site (see attached index page)

Verified that the code snippets matched previous snippets and styling acceptable.

![yoga_gs](https://cloud.githubusercontent.com/assets/691109/24681238/1601fcc8-1949-11e7-8caa-5ac78a4c9a6b.png)
![yoga_index_mobile](https://cloud.githubusercontent.com/assets/691109/24681248/1ee3ea86-1949-11e7-9677-83056f93e385.png)
Closes https://github.com/facebook/yoga/pull/500

Differential Revision: D4834356

Pulled By: emilsjolander

fbshipit-source-id: f47dca4b7518822b195f0bd5076fbf852904372b

docs/_docs/api/csharp.md

@@ -10,25 +10,176 @@ permalink: /docs/api/csharp/
 
 Create a `YogaNode` via its default constructor or the static `Create()` builder method and use `Reset` if you want to pool and re-use nodes. The native memory of a `YogaNode` will automatically be freed when the node is garbage collected.
 
-<script src="https://gist.github.com/emilsjolander/ce73212ee5fdb543d463822c3dd172b4.js"></script>
+```csharp
+YogaNode();
+void Reset();
+
+static YogaNode Create(
+  YogaDirection? styleDirection = null,
+  YogaFlexDirection? flexDirection = null,
+  YogaJustify? justifyContent = null,
+  YogaAlign? alignContent = null,
+  YogaAlign? alignItems = null,
+  YogaAlign? alignSelf = null,
+  YogaPositionType? positionType = null,
+  YogaWrap? wrap = null,
+  YogaOverflow? overflow = null,
+  float? flex = null,
+  float? flexGrow = null,
+  float? flexShrink = null,
+  float? flexBasis = null,
+  Spacing position = null,
+  Spacing margin = null,
+  Spacing padding = null,
+  Spacing border = null,
+  float? Width = null,
+  float? Height = null,
+  float? MaxWidth = null,
+  float? MaxHeight = null,
+  float? MinWidth = null,
+  float? MinHeight = null);
+```
 
 ### Children
 
 The following methods help manage the children of a node.
 
-<script src="https://gist.github.com/emilsjolander/2b0ea738d3c24644fa98910b276620e4.js"></script>
+```csharp
+int Count { get };
+YogaNode this[int index] { get };
+void Insert(int index, YogaNode node);
+void RemoveAt(int index);
+void Clear();
+int IndexOf(YogaNode node);
+```
 
 ### Style getters & setters
 
 The large part of Yoga's API consists of properties, setters, and getters for styles. These all follow the same general structure. Bellow are the function and enums used to control the various styles. For an in depth guide to how each style works see the getting started guide.
 
-<script src="https://gist.github.com/emilsjolander/a84208768e0006b8421a322c40f98539.js"></script>
+```csharp
+enum YogaDirection
+{
+  Inherit,
+  LTR,
+  RTL,
+}
+
+YogaDirection StyleDirection {get, set};
+
+enum YogaFlexDirection
+{
+  Column,
+  ColumnReverse,
+  Row,
+  RowReverse,
+}
+
+YogaFlexDirection FlexDirection {get, set};
+
+enum YogaJustify
+{
+  FlexStart,
+  Center,
+  FlexEnd,
+  SpaceBetween,
+  SpaceAround,
+}
+
+YogaJustify JustifyContent {get, set};
+
+enum YogaAlign 
+{
+  Auto,
+  FlexStart,
+  Center,
+  FlexEnd,
+  Stretch,
+}
+
+YogaAlign AlignItems {get, set};
+YogaAlign AlignSelf {get, set};
+YogaAlign AlignContent {get, set};
+
+enum YogaPositionType 
+{
+  Relative,
+  Absolute,
+}
+
+YogaPositionType PositionType {get, set};
+
+enum YogaWrap 
+{
+  NoWrap,
+  Wrap,
+}
+
+YogaWrap Wrap {get, set};
+
+enum YogaOverflow 
+{
+  Visible,
+  Hidden,
+  Scroll,
+}
+
+YogaOverflow Overflow {get, set};
+
+float Flex {set};
+float FlexGrow {get, set};
+float FlexShrink {get, set};
+float FlexBasis {get, set};
+
+enum YogaEdge 
+{
+  Left,
+  Top,
+  Right,
+  Bottom,
+  Start,
+  End,
+  Horizontal,
+  Vertical,
+  All,
+}
+
+float GetMargin(YogaEdge edge);
+void SetMargin(YogaEdge edge, float margin);
+
+float GetPadding(YogaEdge edge);
+void SetPadding(YogaEdge edge, float padding);
+
+float GetBorder(YogaEdge edge);
+void SetBorder(YogaEdge edge, float border);
+
+float GetPosition(YogaEdge edge);
+void SetPosition(YogaEdge edge, float position);
+
+float Width {get, set};
+float Height {get, set};
+
+float MaxWidth {get, set};
+float MinWidth {get, set};
+
+float MaxHeight {get, set};
+float MinHeight {get, set};
+
+float AspectRatio {get, set};
+```
 
 ### Layout results
 
 Once you have set up a tree of nodes with styles you will want to get the result of a layout calculation. Call `CalculateLayout()` perform layout calculation. Once this function returns the results of the layout calculation is stored on each node. Traverse the tree and retrieve the values from each node.
 
-<script src="https://gist.github.com/emilsjolander/b50acf9fc0877affeb0fc3e55b5c6b4c.js"></script>
+```csharp
+void CalculateLayout();
+float LayoutX {get};
+float LayoutY {get};
+float LayoutWidth {get};
+float LayoutHeight {get};
+YogaDirection LayoutDirection {get};
+```
 
 ### Custom measurements
 
@@ -38,16 +189,53 @@ Certain nodes need to ability to measure themselves, the most common example is
 
 > A measure function can only be attached to a leaf node in the hierarchy.
 
-<script src="https://gist.github.com/emilsjolander/57178307f515e5ea1ccfbedc05df429b.js"></script>
+```csharp
+enum YogaMeasureMode
+{
+  Undefined,
+  Exactly,
+  AtMost,
+}
+
+public delegate long MeasureFunction(
+  YogaNode node,
+  float width,
+  YogaMeasureMode widthMode,
+  float height,
+  YogaMeasureMode heightMode);
+
+class MeasureOutput
+{
+  public static long Make(int width, int height);
+}
+
+void SetMeasureFunction(MeasureFunction measureFunction);
+bool IsMeasureDefined();
+
+bool IsDirty {get};
+void MarkDirty();
+```
 
 ### Data
 
 Data is important when integrating Yoga into another layout system. Data allows you to associate another object with a `YogaNode`. This data can then be retrieved from a `YogaNode` when for example its measure function is called. This is what enables Yoga to rely on the Android system implementations of text measurement in React Native.
 
-<script src="https://gist.github.com/emilsjolander/c099f826623d70fd6bf7dece14e76700.js"></script>
+```csharp
+object Data {get, set}
+```
 
 ### Experiments
 
 Yoga has the concept of experiments. An experiment is a feature which is not yet stable. To enable a feature use the following functions. Once a feature has been tested and is ready to be released as a stable API we will remove its feature flag.
 
-<script src="https://gist.github.com/emilsjolander/97b2500918687826cdfe9429638f2d57.js"></script>
+```csharp
+enum YogaExperimentalFeature {
+  // Current experiments
+}
+
+static void setExperimentalFeatureEnabled(
+  YogaExperimentalFeature feature, 
+  boolean enabled);
+static boolean isExperimentalFeatureEnabled(
+  YogaExperimentalFeature feature);
+```