Is your feature request related to a problem? Please describe.

As I said here:

In spacemacs you have major-modes, like "python", "markdown", and so on. So for example if you open a .md file, spacemacs will use Markdown mode in that buffer.

When you are using a mode, key bindings under <spc> m or under , will be unique to that mode.

This means that when you are editing a markdown, <spc> m b could be assigned to "make bold", while in python <spc> m b could be assigned to "toggle breakpoint" (I am just inventing).

Describe the solution you'd like

In vscode-which-key/#14 we have enabled the possibility to have major mode key bindings. Now it's time to write them!

These are some of the most important programming languages where a major mode is missing:

• javascript
• python
• java - eric on it
• go
• cpp
• ObjectPascal
• typescript
• php
• c#
• c
• shell
• scala
• rust
• clojure
• ruby
• F#
• R
• jsx, tsx

markup languages:

• markdown
• org mode

If you want to start working on a major mode that is (or isn't) listed here, please leave a comment.
In this way we don't overlap with each other.

Additional context

• In 23b5b75 you can find an example of a markdown major mode binding.
• top vs code extensions