Help: Document CMAKE_PDB_OUTPUT_DIRECTORY_<CONFIG> variable

Help/manual/cmake-variables.7.rst

@@ -204,6 +204,7 @@ Variables that Control the Build
    /variable/CMAKE_NO_BUILTIN_CHRPATH
    /variable/CMAKE_NO_SYSTEM_FROM_IMPORTED
    /variable/CMAKE_PDB_OUTPUT_DIRECTORY
+   /variable/CMAKE_PDB_OUTPUT_DIRECTORY_CONFIG
    /variable/CMAKE_POSITION_INDEPENDENT_CODE
    /variable/CMAKE_RUNTIME_OUTPUT_DIRECTORY
    /variable/CMAKE_SHARED_LINKER_FLAGS_CONFIG

Help/variable/CMAKE_PDB_OUTPUT_DIRECTORY_CONFIG.rst

@@ -0,0 +1,10 @@
+CMAKE_PDB_OUTPUT_DIRECTORY_<CONFIG>
+-----------------------------------
+
+Per-configuration output directory for MS debug symbols ``.pdb`` files.
+
+This is a per-configuration version of :variable:`CMAKE_PDB_OUTPUT_DIRECTORY`.
+This variable is used to initialize the
+:prop_tgt:`PDB_OUTPUT_DIRECTORY_<CONFIG>`
+property on all the targets.  See that target property for additional
+information.