Fix type-check and add readonly to document inferrence

Author: ShukantPal

packages/webdoc-parser/src/transformer/symbol-to-doc.js

@@ -138,6 +138,7 @@ export default function symbolToDoc(symbol: Symbol): ?Doc {
   options.access = symbol.meta.access;
   options.dataType = symbol.meta.dataType;
   options.defaultValue = symbol.meta.defaultValue;
+  options.readonly = symbol.meta.readonly;
   options.scope = symbol.meta.scope;
   options.loc = symbol.loc;
 

packages/webdoc-parser/src/types/Symbol.js

@@ -30,6 +30,7 @@ export type SymbolSignature = {
   implements?: ?Array<string | Symbol>,
   object?: ?string,
   params?: ?Array<$Shape<Param>>,
+  readonly?: boolean,
   returns?: ?Array<$Shape<Return>>,
   scope?: ?string,
   value?: ?string,