feat: document code fragment rules (#309)

* feat: document code fragment rules

This commit adds a basic style guide to the contributing
documentation, with rules around how we currently do executable code
fragments.

Resolves #239

* revert: header level in contributing

* revert: change to section header

Author: vados-cosmonic

CONTRIBUTING.md

@@ -52,6 +52,28 @@ mdbook build
 
 Don't forget to remove the changes in `book.toml` before you commit!
 
+## Writing style guide
+
+This section contains what is a *somewhat loosely* applied style guide for writing that is contributed to `component-docs`.
+
+### Executable code fragments
+
+For code that should be executed by the user in their console of choice, prefer using `sh`/`bash`. While not every user's
+shell is `sh` or `bash` (with `zsh` being incredilby common), `sh`/`bash` provide a decent approximation.
+
+Importantly, code that is meant to be executed should be copy-pastable -- and should not contain `$` as a prefix. For example:
+
+```sh
+echo 'this is an example';
+```
+
+On the other hand, when commands *and* output are shown, use `console` and *do* prefix the command with `$` to differentiate it (or `#` in a sudo context):
+
+```console
+$ echo 'this is an example';
+this is an example
+```
+
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