Use case or problem
Many different plugins implement code block handlers, but it’s not trivial to remember the proper syntax for their configuration / usage.
Proposed solution
The Obsidian API could offer a standard way for registerMarkdownCodeBlockProcessor() calls to add a documentation link and/or cheat-sheet snippet.
When editing a code block of that particular type, Obsidian could display a 
Hints / Help icon to either show the cheat-sheet in a popover, or open the documentation website in the default browser.
Current workaround (optional)
Manually find the documentation or create your own cheat-sheets in the vault.