By convention, code markup (`~`) is reserved for keybindings in Org-based
documentation in Spacemacs. Verbatim markup (`=`) is reserved for code and
other code-like things. So change several readmes to reflect this convention.
Use verbatim markup for things like (non-exhaustive list):
- Emacs Lisp functions, modes, buffers, etc.
- Environment variables
- Directory paths
- Code in general
It is an Emacs-wide convention to use `RET` when referring to the act of
pressing the return key. Spacemacs seems to follow that convention as well. So
fix some Org files that were deviating from this convention.
In particular, replace usages of `<return>` and `return` with `RET`.
Also update the description of an `M-RET` keybinding[1] based on the docstring
of `ido-select-text`.
[1]: Suggested-by: bmag <bmag@users.noreply.github.com>
