Fix typo

INSTALL

@@ -155,8 +155,8 @@ The configure script will also use your environmental
 variables for determining compiler/linker options.   This can
 be used to manual specify features and compilation options.
 
-WARNING: Executable built in your environment may not run
-	in your user's environments.  The portability of
+WARNING: Executables built in your environment may not run
+	in your users' environments.  The portability of
 	executables between environments is your responsibility.
 
 Supported Environmental Variables