Help: Convert project() directory variables to a definition list

Help/command/project.rst

@@ -20,12 +20,13 @@ Sets the name of the project, and stores it in the variable
 ``CMakeLists.txt`` also stores the project name in the
 variable :variable:`CMAKE_PROJECT_NAME`.
 
-Also sets the variables
+Also sets the variables:
 
-* :variable:`PROJECT_SOURCE_DIR`,
-  :variable:`<PROJECT-NAME>_SOURCE_DIR`
-* :variable:`PROJECT_BINARY_DIR`,
-  :variable:`<PROJECT-NAME>_BINARY_DIR`
+:variable:`PROJECT_SOURCE_DIR`, :variable:`<PROJECT-NAME>_SOURCE_DIR`
+  Absolute path to the source directory for the project.
+
+:variable:`PROJECT_BINARY_DIR`, :variable:`<PROJECT-NAME>_BINARY_DIR`
+  Absolute path to the binary directory for the project.
 
 Further variables are set by the optional arguments described in the following.
 If any of these arguments is not used, then the corresponding variables are