Expand/consolidate "detecting bootc"

[cgwalters]

Continually comes up.

[gemini-code-assist]

Code Review

This pull request consolidates and expands the documentation on detecting bootc systems, which is a helpful clarification. The changes move detection logic into a single file and add more methods. I've found a couple of areas in the new documentation that could be improved for clarity and correctness.

[gemini-code-assist]

The phrasing in this new section is a bit ambiguous. The term 'will differentiate' doesn't clearly explain what is being differentiated. For better readability, it would be helpful to explicitly state what this check accomplishes.

Additionally, this section seems to partially duplicate the information in the 'Detecting bootc specifically' section later in this document (lines 86-95). It would be beneficial to consolidate these sections to avoid redundancy and potential confusion for readers.

Suggested change

	If you want to specifically detect if bootc is in use, then
	if the binary is present, the following example of
	parsing the JSON status will differentiate:
	`test $(bootc status --format=json | jq .spec.image) = null`.
	To specifically detect if bootc is in use, you can parse its JSON status
	(if the binary is present) to tell if a system is tracking an image.
	The following command succeeds if an image is *not* being tracked:
	`test $(bootc status --format=json | jq .spec.image) = null`.

[gemini-code-assist]

There's a typo in 'recomendations'.

Suggested change

	should instead detect via one of the recomendations above.
	should instead detect via one of the recommendations above.