Follow-up from "Fixes parsing of chained OR/AND conditions in input rules"

Improve documentation for input examples

The following discussion from !217978 (merged) should be addressed:

• @lauraXD started a discussion: (+1 comment)

  As a sidenote, this section is getting really big, it might be a good idea (in a followup) for us to take these two big examples and move them to https://docs.gitlab.com/ci/inputs/examples/, and leave a smaller example behind that's easier to follow for this feature section.