docs: register v9 endpoints to DISCORD_ROADMAP.md
- [x] [Delete Pinned Channel Message](https://discord.com/developers/docs/resources/channel#delete-pinned-channel-message)
- [ ] [Group DM Add Recipient](https://discord.com/developers/docs/resources/channel#group-dm-add-recipient)
- [ ] [Group DM Remove Recipient](https://discord.com/developers/docs/resources/channel#group-dm-remove-recipient)
+- [ ] [Start Thread with Message](https://discord.com/developers/docs/resources/channel#start-thread-with-message)
+- [ ] [Start Thread without Message](https://discord.com/developers/docs/resources/channel#start-thread-without-message)
+- [ ] [Join Thread](https://discord.com/developers/docs/resources/channel#join-thread)
+- [ ] [Add Thread Member](https://discord.com/developers/docs/resources/channel#add-thread-member)
+- [ ] [Leave Thread](https://discord.com/developers/docs/resources/channel#leave-thread)
+- [ ] [Remove Thread Member](https://discord.com/developers/docs/resources/channel#remove-thread-member)
+- [ ] [List Thread Members](https://discord.com/developers/docs/resources/channel#list-thread-members)
+- [ ] [List Active Threads](https://discord.com/developers/docs/resources/channel#list-active-threads)
+- [ ] [List Public Archived Threads](https://discord.com/developers/docs/resources/channel#list-public-archived-threads)
+- [ ] [List Private Archived Threads](https://discord.com/developers/docs/resources/channel#list-private-archived-threads)
+- [ ] [List Joined Private Arhived Threads](https://discord.com/developers/docs/resources/channel#list-joined-private-archived-threads)
### [Emoji Resource](https://discord.com/developers/docs/resources/emoji#emoji-resource)
- [x] [Emoji Object](https://discord.com/developers/docs/resources/emoji#emoji-object)
- [x] [List Guild Emojis](https://discord.com/developers/docs/resources/emoji#list-guild-emojis)
