Implement linking to types in markdown

[Sven65]

Please Describe The Problem To Be Solved

If a given type is found inside the final doc before markdown generation, the markdown should link to it.

For example, if the type TBChannelId has been parsed and documented, the below markdown

# Attributes
- channel_id :: TBChannelId
- description :: &str
- emoji :: TBGuildWelcomeChannelEmoji?

should be made into

# Attributes
- channel_id :: [TBChannelId](./TBChannelId.md)
- description :: &str
- emoji :: TBGuildWelcomeChannelEmoji?