docs: add tasks

docs/src/docPages/api/extensions/suggestion.md

@@ -2,8 +2,9 @@
 
 TODO
 
-- mentions
-- hashtags
-- emojis
-- snippets
-- variables
+- mentions (as text or as/with user ID)
+- hashtags (as text)
+- emojis (input rule with an autocomplete popup)
+- commands (can only be triggered at the beginning of a line, should trigger custom commands)
+- snippets (should be able to insert multiple paragraphs)
+- variables (should replaced when copied to external sources)