Document how to use vim remap

[stevenguh]

Split from VSpaceCode/VSpaceCode#90 (comment)

We are not documenting how to use vim.remap in overrides and in the regular binding

There are two primary ways to use it:
https://github.com/VSpaceCode/VSpaceCode/blob/v0.7.5/package.json#L106-L117
https://github.com/VSpaceCode/VSpaceCode/blob/v0.7.5/package.json#L1044-L1056

[stevenguh]

Base on VSpaceCode/vscode-which-key#15 (comment) , we should also mention if a user changed it's leader key, the default easy motion command might not work.

[marcoieni]

This should be closed because #15 has been merged, right?

[stevenguh]

right. thanks for the reminder.