GRAILS-8657: Add info on how to use custom css, js and html for project documentation

[graemerocher]

Original Reporter: ronnylovtangen
Environment: Not Specified
Version: 2.0 final
Migrated From: http://jira.grails.org/browse/GRAILS-8657

It is possible to use custom css, js and html for project documentation by setting properties grails.doc.css, grails.doc.js and grails.doc.style.
This information is [missing from the documentation|http://grails.org/doc/2.0.0/guide/conf.html#docengine].

User list thread: http://grails.1312388.n4.nabble.com/grails-doc-not-compatible-with-current-grails-core-td4263201.html#a4299020

[graemerocher]

pledbrook said:
Added in the [master|https://github.com/grails/grails-doc/commit/a860c970bc7ca26437e094b7ef00575b3ea5b03e] and [2.0.x|https://github.com/grails/grails-doc/commit/ca30e44108edb589937c3b0d3c2a077418f98cba] branches. It could do with some more fleshing out, particularly on the HTML template front (for example it could describe all the variables available in the templates).