Too deep to read: some of the plugins documents

for example:

When I want to read the documents for spring-security-core, I have to:

1. search it from homepage
2. open http://plugins.grails.org/plugin/grails/spring-security-core from search results
3. click a link to open http://grails-plugins.github.io/grails-spring-security-core/
4. click a link to open "User Guide"
5. read it.

What I expect is:

1. there is a list of commonly used plugins
2. click a link can directly open the corresponding documents.

Start at the Grails homepage and trace the current search-results path to the spring-security-core plugin page, then to its User Guide. Review how commonly used plugins and their documentation links are presented. Done means a newcomer can find a plugin from the homepage and open its documentation directly, without navigating through multiple intermediate pages.

Written by the indexing model from the issue text.