Improve config.assets.initialize_on_precompile guide.

guides/source/asset_pipeline.textile

@@ -409,9 +409,9 @@ cannot see application objects or methods. *Heroku requires this to be false.*
 WARNING: If you set +config.assets.initialize_on_precompile+ to false, be sure to
 test +rake assets:precompile+ locally before deploying. It may expose bugs where
 your assets reference application objects or methods, since those are still
-in scope in development mode regardless of the value of this flag. Changing this flag also effects
+in scope in development mode regardless of the value of this flag. Changing this flag also affects
 engines. Engines can define assets for precompilation as well. Since the complete environment is not loaded,
-engines (or other gems) will not be loaded which can cause missing assets.
+engines (or other gems) will not be loaded, which can cause missing assets.
 
 Capistrano (v2.8.0 and above) includes a recipe to handle this in deployment. Add the following line to +Capfile+: