Help: Add explicit <PackageName>_ROOT variable documentation

Add documentation for both the CMake variable and environment variable
of this name pattern.  Update references to these names to link to their
documents.  Clarify the pattern used to construct their names.

1 files changed, 8 insertions, 7 deletions

diff --git a/Help/policy/CMP0074.rst b/Help/policy/CMP0074.rst
index ffac4a7..896936b 100644
--- a/Help/policy/CMP0074.rst
+++ b/Help/policy/CMP0074.rst
@@ -1,18 +1,19 @@
 CMP0074
 -------
 
-:command:`find_package` uses ``PackageName_ROOT`` variables.
+:command:`find_package` uses ``<PackageName>_ROOT`` variables.
 
-In CMake 3.12 and above the ``find_package(PackageName)`` command now searches
-a prefix specified by a ``PackageName_ROOT`` CMake or environment variable.
+In CMake 3.12 and above the :command:`find_package(<PackageName>)` command now
+searches prefixes specified by the :variable:`<PackageName>_ROOT` CMake
+variable and the :envvar:`<PackageName>_ROOT` environment variable.
 Package roots are maintained as a stack so nested calls to all ``find_*``
 commands inside find modules also search the roots as prefixes.  This policy
 provides compatibility with projects that have not been updated to avoid using
-``PackageName_ROOT`` variables for other purposes.
+``<PackageName>_ROOT`` variables for other purposes.
 
-The ``OLD`` behavior for this policy is to ignore ``PackageName_ROOT``
-variables.  The ``NEW`` behavior for this policy is to use ``PackageName_ROOT``
-variables.
+The ``OLD`` behavior for this policy is to ignore ``<PackageName>_ROOT``
+variables.  The ``NEW`` behavior for this policy is to use
+``<PackageName>_ROOT`` variables.
 
 This policy was introduced in CMake version 3.12.  CMake version
 |release| warns when the policy is not set and uses ``OLD`` behavior.