[lldb][Docs] Link up the newly restored data formatters page

In the place it used to be linked from.

Author: DavidSpickett

lldb/docs/resources/dataformatters.rst

@@ -4,8 +4,7 @@ Data Formatters
 This page is an introduction to the design of the LLDB data formatters
 subsystem. The intended target audience are people interested in understanding
 or modifying the formatters themselves rather than writing a specific data
-formatter. For this latter purpose, the user documentation about formatters is
-the main relevant document which one should refer to.
+formatter. For the latter, refer to :doc:`/use/variable/`.
 
 This page also highlights some open areas for improvement to the general
 subsystem, and more evolutions not anticipated here are certainly possible.

lldb/docs/resources/overview.rst

@@ -92,7 +92,9 @@ layers to the implementation: DataVisualization at the highest end of the
 spectrum, backed by classes implementing individual formatters, matching rules,
 etc.
 
-For an introduction to data formatters, see :doc:`/use/variable`.
+For a general user-level introduction to data formatters, see :doc:`/use/variable`.
+
+More details on their architecture can be found in :doc:`/resources/dataformatters`.
 
 Expression
 ----------