After merging [this PR](https://github.com/Silex/docker.el/pull/39), the
`docker.el` package now supports integration with `docker-compose`. This
commit adds a keybinding for `docker-compose`, which allows us to
interact with compose files for the current project.
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
