Readme cleanup

[firai]

• Key binding lists
  • Fix the "Esc, Ctrl-[" key binding, which would have meant pressing these in succession, to say "Esc or Ctrl-[".
  • Reword the descriptions of "Shift-Esc" and "Esc or Ctrl-[" to be more accurate.
  • Reword the descriptions for changing cell type to be similar to those in JupyterLab.
  • Consistency in abbreviations and capitalization
    • Esc
    • Cmd
  • Reorder vim bindings and Jupyter command bindings to put the corresponding bindings in the same order.
• Elsewhere
  • Fix grammar in various places.
  • Flip order of Normal and Insert modes in the mode list, based on the order that they are entered relative to Command mode, i.e., how they would be ordered in a flow diagram.
  • Change the key binding explanation to use <kbd> tags based on semantics. (However, to retain consistency with the style in vim help files, the key bindings in the lists still use hyphens between the keys.)
  • Uniformly make mode names capitalized and "mode" itself lowercase in paragraph text. (Key binding descriptions have been left as title case only to minimize change. I wouldn't be opposed to making these sentence case.)

[github-actions]

👈 Launch a Binder on branch firai/jupyterlab-vim/readme-cleanup