Added nested FlexBuffer parsing

Change-Id: I918b66eb5646d035e3aae675f745802eb54b03ea

docs/source/FlexBuffers.md

@@ -128,6 +128,16 @@ A description of how FlexBuffers are encoded is in the
 [internals](Internals.md#flexbuffers) document.
 
 
+# Nesting inside a FlatBuffer
+
+You can mark a field as containing a FlexBuffer, e.g.
+
+    a:[ubyte] (flexbuffer);
+
+A special accessor will be generated that allows you to access the root value
+directly, e.g. `a_flexbuffer_root().AsInt64()`.
+
+
 # Efficiency tips
 
 * Vectors generally are a lot more efficient than maps, so prefer them over maps

docs/source/Schemas.md

@@ -302,6 +302,9 @@ Current understood attributes:
     (which must be a vector of ubyte) contains flatbuffer data, for which the
     root type is given by `table_name`. The generated code will then produce
     a convenient accessor for the nested FlatBuffer.
+-   `flexbuffer` (on a field): this indicates that the field
+    (which must be a vector of ubyte) contains flexbuffer data. The generated
+    code will then produce a convenient accessor for the FlexBuffer root.
 -   `key` (on a field): this field is meant to be used as a key when sorting
     a vector of the type of table it sits in. Can be used for in-place
     binary search.