Fixing a documentation typo, DIRS -> DIR in HINTS variables.

Change-Id: I42b75a5e0b8a451c3a43ab29d0c14856e4b86ab8

cmake/FindGlog.cmake

diff --git a/cmake/FindGlog.cmake b/cmake/FindGlog.cmake
index 85c3f06..0dde218 100644
--- a/cmake/FindGlog.cmake
+++ b/cmake/FindGlog.cmake
@@ -39,10 +39,10 @@
 #
 # The following variables control the behaviour of this module:
 #
-# GLOG_INCLUDE_DIRS_HINTS: List of additional directories in which to
-#                          search for glog includes, e.g: /timbuktu/include.
-# GLOG_LIBRARY_DIRS_HINTS: List of additional directories in which to
-#                          search for glog libraries, e.g: /timbuktu/lib.
+# GLOG_INCLUDE_DIR_HINTS: List of additional directories in which to
+#                         search for glog includes, e.g: /timbuktu/include.
+# GLOG_LIBRARY_DIR_HINTS: List of additional directories in which to
+#                         search for glog libraries, e.g: /timbuktu/lib.
 #
 # The following variables are also defined by this module, but in line with
 # CMake recommended FindPackage() module style should NOT be referenced directly