Update references to variables in docs (#1238)

Update references to variables in docs (#1238)

* Update navbar variables in component docs page

* Update pagination variables in component docs page

* Update tabs variables in component docs page

* Update button variables in element docs page

* Update table variables in element docs page

* Update title variables in element docs page

* Update variables template to support layout

* Add section variables in relevant docs page

* Add footer variables in relevant docs page

* Update variables template to support custom messages

* Add form generic variables in relevant docs page

* Update derived variables in relevant docs page

* Add generic variables to variables docs page

* Update sass files count in docs Modular page