Docs: Add Explicit addressing to Readme and changelog.

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [unreleased]
 ### Added
+- Explicit addressing option for posting.
 - Optional SSH access mode. (Needs `erlang-ssh` package on some distributions).
 - [MongooseIM](https://github.com/esl/MongooseIM) http authentication support.
 - LDAP authentication

docs/api/differences_in_mastoapi_responses.md

@@ -69,6 +69,7 @@ Additional parameters can be added to the JSON body/Form data:
 
 - `preview`: boolean, if set to `true` the post won't be actually posted, but the status entitiy would still be rendered back. This could be useful for previewing rich text/custom emoji, for example.
 - `content_type`: string, contain the MIME type of the status, it is transformed into HTML by the backend. You can get the list of the supported MIME types with the nodeinfo endpoint.
+- `to`: A list of nicknames (like `lain@soykaf.club` or `lain` on the local server) that will be used to determine who is going to be addressed by this post. Using this will disable the implicit addressing by mentioned names in the `status` body, only the people in the `to` list will be addressed. The normal rules for for post visibility are not affected by this and will still apply.
 
 ## PATCH `/api/v1/update_credentials`