Some grammatical changes.

Author: Satish Kamath

docs/test-suite/installation-configuration.md

@@ -23,7 +23,7 @@ The EESSI test suite requires
 
     * You can install a more recent version of Python on top of the GCC/GCCcore compiler.
     * You can install a ReFrame module with EasyBuild and a [ReFrame easyconfig](https://github.com/easybuilders/easybuild-easyconfigs/tree/develop/easybuild/easyconfigs/r/ReFrame) containing a more recent Python version.
-    * Don't forget to set RFM_PURGE_ENVIRONMENT=1 if you use Python from a module. The ReFrame easyconfigs already do that for you.
+    * Set RFM_PURGE_ENVIRONMENT=1 if you use Python from a module. The ReFrame easyconfigs automatically do that for you.
 
 #### Installing Reframe