Fix broken links in grails-data/gorm documentation

[jamesfredley]

Issue description

Broken links can be identified and verified as fixed using https://github.com/lycheeverse/lychee/releases/.

./gradlew grails-doc:build
cd \grails-doc\build\docs\grails-data
lychee-x86_64-windows.exe . --format markdown --output results.md --exclude-path api --exclude-path grails-data/hibernate5/api --exclude ".*.css$" --exclude "^http://localhost"

review results.md

[jdaugherty]

@jamesfredley are there still broken links or is this issue actually fixed now? May I suggest that @Ajay9704 take this if it's not?

[jamesfredley]

There are still broken links. This ticket will likely take a few iterative PRs, given the broken links are coming from adoc, groovydoc, etc.

[Ajay9704]

@jdaugherty , @jamesfredley I've submitted a pull request that addresses this issue, please review and let me know if anything is required from my end