Add a section on how to identify a pleroma instance, clarify that post upload...

Add a section on how to identify a pleroma instance, clarify that post upload limit is not capped too

docs/Differences-in-MastodonAPI-Responses.md

 # Differences in Mastodon API responses from vanilla Mastodon
 
+A Pleroma instance can be identified by "<Mastodon version> (compatible; Pleroma <version>)" present in `version` field in response from `/api/v1/instance` 
+
 ## Flake IDs
 
 Pleroma uses 128-bit ids as opposed to Mastodon's 64 bits. However just like Mastodon's ids they are sortable strings
 
 ## Attachment cap
 
-Some apps operate under the assumption that no more than 4 attachments ccan be returned, however Pleroma can return any amount of attachments
+Some apps operate under the assumption that no more than 4 attachments ccan be returned or uploaded. Pleroma however does not enforce any limits on attachment count neither when returning the status object nor when posting.