Additional version banner details.

[jcapriot]

Adds a more detailed descriptions on what causes different messages to appear in the version announcement.

This tripped me up for a little bit and I had to go searching in the source code to find out what exactly triggered the development warning banner to display. So this PR is in the hope of avoiding a small headache for others!

[jcapriot]

These are the logic lines I am referring to:

pydata-sphinx-theme/src/pydata_sphinx_theme/assets/scripts/pydata-sphinx-theme.js

Lines 588 to 602 in 7ed0ca4

	const isDev =
	version.includes("dev") ||
	version.includes("rc") ||
	version.includes("pre");
	const newerThanPreferred =
	versionsAreComparable && compare(version, preferredVersion, ">");
	if (isDev || newerThanPreferred) {
	bold.innerText = "an unstable development version";
	} else if (versionsAreComparable && compare(version, preferredVersion, "<")) {
	bold.innerText = `an old version (${version})`;
	} else if (!version) {
	bold.innerText = "an unknown version"; // e.g., an empty string
	} else {
	bold.innerText = `version ${version}`;
	}

[trallard]

Thanks for your contribution 🙏🏽 I think this definitely makes the criteria clear for folks (this has been a tricky one to get across).

All looks good so will approve and merge right away

[Carreau]

Failure is unrelated. merging.

[jcapriot]

Happy to help!