Improve handling/wording of package-with-huge-docs on javadocs

[jengelh]

[   40s] xz-java-javadoc.noarch: W: package-with-huge-docs: 100%

The 100% documentation ratio is sort of expected with such a package. Options I see:

• Add an explanatory line to rpmlint pointing to the policy, e.g. Documentation should be in a package ending in "-doc"
• Whitelist -javadoc as a suffix in rpmlint

(I am kind of in favor of the first, because javadoc is redundant when there is already a -java substring.)

[Conan-Kudo]

We should probably do the latter regardless, as -doc and -javadoc can be two different types.