add alwaysShowSend (#1173)

As now the alwaysShowSend property work again, I re-add it to the docs

README.md

@@ -163,6 +163,7 @@ e.g. System Message
 - **`messageIdGenerator`** _(Function)_ - Generate an id for new messages. Defaults to UUID v4, generated by [uuid](https://github.com/kelektiv/node-uuid)
 - **`user`** _(Object)_ - User sending the messages: `{ _id, name, avatar }`
 - **`onSend`** _(Function)_ - Callback when sending a message
+- **`alwaysShowSend`** _(Bool)_ - Always show send button in input text composer; default `false`, show only when text input is not empty
 - **`locale`** _(String)_ - Locale to localize the dates
 - **`timeFormat`** _(String)_ - Format to use for rendering times; default is `'LT'`
 - **`dateFormat`** _(String)_ - Format to use for rendering dates; default is `'ll'`