Help: Replace `cmake -P` option mentions w/ Sphinx role

Help/variable/CMAKE_BINARY_DIR.rst

@@ -7,7 +7,7 @@ This is the full path to the top level of the current CMake build
 tree.  For an in-source build, this would be the same as
 :variable:`CMAKE_SOURCE_DIR`.
 
-When run in -P script mode, CMake sets the variables
+When run in :option:`-P <cmake_P -P>` script mode, CMake sets the variables
 :variable:`CMAKE_BINARY_DIR`, :variable:`CMAKE_SOURCE_DIR`,
 :variable:`CMAKE_CURRENT_BINARY_DIR` and
 :variable:`CMAKE_CURRENT_SOURCE_DIR` to the current working directory.

Help/variable/CMAKE_CURRENT_BINARY_DIR.rst

@@ -9,7 +9,7 @@ create a binary directory in the build tree, and as it is being
 processed this variable will be set.  For in-source builds this is the
 current source directory being processed.
 
-When run in -P script mode, CMake sets the variables
+When run in :option:`-P <cmake_P -P>` script mode, CMake sets the variables
 :variable:`CMAKE_BINARY_DIR`, :variable:`CMAKE_SOURCE_DIR`,
 :variable:`CMAKE_CURRENT_BINARY_DIR` and
 :variable:`CMAKE_CURRENT_SOURCE_DIR` to the current working directory.

Help/variable/CMAKE_CURRENT_SOURCE_DIR.rst

@@ -6,7 +6,7 @@ The path to the source directory currently being processed.
 This is the full path to the source directory that is currently being
 processed by cmake.
 
-When run in -P script mode, CMake sets the variables
+When run in :option:`-P <cmake_P -P>` script mode, CMake sets the variables
 :variable:`CMAKE_BINARY_DIR`, :variable:`CMAKE_SOURCE_DIR`,
 :variable:`CMAKE_CURRENT_BINARY_DIR` and
 :variable:`CMAKE_CURRENT_SOURCE_DIR` to the current working directory.

Help/variable/CMAKE_SOURCE_DIR.rst

@@ -7,7 +7,7 @@ This is the full path to the top level of the current CMake source
 tree.  For an in-source build, this would be the same as
 :variable:`CMAKE_BINARY_DIR`.
 
-When run in ``-P`` script mode, CMake sets the variables
+When run in :option:`-P <cmake_P -P>` script mode, CMake sets the variables
 :variable:`CMAKE_BINARY_DIR`, :variable:`CMAKE_SOURCE_DIR`,
 :variable:`CMAKE_CURRENT_BINARY_DIR` and
 :variable:`CMAKE_CURRENT_SOURCE_DIR` to the current working directory.