Update usage documention for pginclude

Author: bmomjian

src/tools/pginclude/README

@@ -1,13 +1,15 @@
-These utilities help clean up #include file usage:
+These utilities help clean up #include file usage.  They should be run
+in this order so that the include files have the proper includes before
+the C files are tested.
 
 pgfixinclude	change #include's to <> or ""
 
-pgrminclude [-v]
-		remove extra #include's
-
 pgcompinclude [-v]
 		report which #include files can not compile on their own
 
+pgrminclude [-v]
+		remove extra #include's
+
 pgdefine	create macro calls for all defines in the file (used by
 		the above routines)