Added fenced code blocks to the C++/Java/Go docs for syntax highlighting.

Change-Id: I504915c6b5367e8c05dc056463158b8420ad8c5e
Tested: on Linux.

docs/source/GoUsage.md

@@ -7,6 +7,7 @@ See `go_test.go` for an example. You import the generated code, read a
 FlatBuffer binary file into a `[]byte`, which you pass to the
 `GetRootAsMonster` function:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     import (
        example "MyGame/Example"
        flatbuffers "github.com/google/flatbuffers/go"
@@ -17,11 +18,14 @@ FlatBuffer binary file into a `[]byte`, which you pass to the
     buf, err := ioutil.ReadFile("monster.dat")
     // handle err
     monster := example.GetRootAsMonster(buf, 0)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Now you can access values like this:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     hp := monster.Hp()
     pos := monster.Pos(nil)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Note that whenever you access a new object like in the `Pos` example above,
 a new temporary accessor object gets created. If your code is very performance
@@ -34,21 +38,28 @@ To access vectors you pass an extra index to the
 vector field accessor. Then a second method with the same name suffixed
 by `Length` let's you know the number of elements you can access:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     for i := 0; i < monster.InventoryLength(); i++ {
         monster.Inventory(i) // do something here
     }
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 You can also construct these buffers in Go using the functions found in the
 generated code, and the FlatBufferBuilder class:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     builder := flatbuffers.NewBuilder(0)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Create strings:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     str := builder.CreateString("MyMonster")
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Create a table with a struct contained therein:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     example.MonsterStart(builder)
     example.MonsterAddPos(builder, example.CreateVec3(builder, 1.0, 2.0, 3.0, 3.0, 4, 5, 6))
     example.MonsterAddHp(builder, 80)
@@ -58,6 +69,7 @@ Create a table with a struct contained therein:
     example.MonsterAddTest(builder, mon2)
     example.MonsterAddTest4(builder, test4s)
     mon := example.MonsterEnd(builder)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 Unlike C++, Go does not support table creation functions like 'createMonster()'.
 This is to create the buffer without
@@ -72,11 +84,13 @@ will be `a`, `c` and `d`.
 Vectors also use this start/end pattern to allow vectors of both scalar types
 and structs:
 
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.go}
     example.MonsterStartInventoryVector(builder, 5)
     for i := 4; i >= 0; i-- {
         builder.PrependByte(byte(i))
     }
     inv := builder.EndVector(5)
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 The generated method 'StartInventoryVector' is provided as a convenience
 function which calls 'StartVector' with the correct element size of the vector