core: include trailing "_" and "!" characters in links (#6973)

* core: include trailing "_" and "!" characters in links

* docs: plan for keeping trailing "_" and "!" in links

src/Simplex/Chat/Markdown.hs

@@ -302,6 +302,8 @@ markdownP = mconcat <$> A.many' fragmentP
     isPunctuation' = \case
       '/' -> False
       ')' -> False
+      '_' -> False
+      '!' -> False
       c -> isPunctuation c
     isUri s = T.length s >= 10 && any (`T.isPrefixOf` s) ["http://", "https://", "simplex:/"]
     -- matches what is likely to be a domain, not all valid domain names