Docs: Document forbid for no-unescaped-entities rule (jsx-eslint#1263)

Author: alexilyaev

docs/rules/no-unescaped-entities.md

@@ -68,3 +68,19 @@ The following patterns are **not** considered warnings:
 ```jsx
 <div> {'>'} </div>
 ```
+
+## Rule Options
+
+```js
+...
+"react/no-unescaped-entities": [<enabled>, { "forbid": Array<string> }]
+...
+```
+
+### `forbid`
+
+Overwrite the default forbidden entities array `['>', '"', '\'', '}']` with your own:
+
+```js
+"react/no-unescaped-entities": ["error", {"forbid": [">", "}"]}],
+```