feat: add a preprocessor for alerts

[CommanderStorm]

For a few parts of our docs, I would like to have alerts.

this looks like this:

Related to

• docs: postgres with certificates recipy #1922

[CommanderStorm]

Suggested change

	- name: Setup mdBook
	uses: peaceiris/actions-mdbook@v2
	with:
	mdbook-version: '0.4.40'
	mdbook-version: '0.4.51'
	- name: Install mdbook-alerts
	run: cargo install mdbook-alerts
	- uses: taiki-e/install-action@v2
	with: { tool: mdbook }
	- name: Install mdbook-alerts
	run: cargo binstall mdbook-alerts

[nyurik]

lets do the minor binstall change, and free to merge