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

docs/documentation/elements/table.html

@@ -16,8 +16,6 @@ variables:
   value: 0.5em 0.75em
 - name: $table-cell-heading-color
   value: $text-strong
-- name: $table-head-color
-  value: $grey
 - name: $table-head-cell-border-width
   value: 0 0 2px
 - name: $table-head-cell-color