Docs - Multiple issues with Tag Library documentation

[matrei]

Issue description

• Examples of using inherited properties in Tag Libraries uses Controllers (except in pageScope page)
• Links are broken in request, response, servletContext and session pages

[dauer]

I have opened a pull request for review https://github.com/apache/grails-core/pull/15304/files

I think the original examples where copied from the controller documentation, they were not 1:1 when changed to TagLib examples.