GH#553: Clarifying callout options to show more flexibility

[bergerhoffer]

Issue:
#553

Additional information:

Preview (VPN required): https://file.corp.redhat.com/~ahoffer/2024/main.html#explain-commands-variables-in-code-blocks

I made the following updates:

• In the bulleted list option, changed "YAML file" to "code block", so that it doesn't seem like you have to use the bulleted list for all YAML blocks
• In the description list option, removed the rule that says descriptions must start exactly with "Specifies". And instead allowed more flexibility - pulled in the guidance from the ISG that says it can be a full sentence, or a fragment starting either with a noun phrase or a third-person verb (such as "Specifies")

[bergerhoffer]

@IngridT1 @Preeticp Sorry for the extreme delay on getting this open. I re-reviewed the comments on the issue and our slack conversation from the fall.

I think that @Preeticp's suggestion to just change "YAML file" to a more generic "code block" fixes our concerns with it seeming like you have to use the bulleted list option for YAML.

Also as discussed in the slack thread, I adjusted the wording so that it doesn't say that you have to use "Specifies" exactly. I updated to match what the ISG recommends.

Please let me know if you have any feedback. I've added a preview build in the description of the PR.

[IngridT1]

LGTM. I'll let @Preeticp take a look at it before I merge it.