Fix typos and formatting

Author: Arie Marie 'Thomas' Dalleis

examples/flaskr/README

@@ -10,7 +10,7 @@
     ~ How do I use it?
 
       1. edit the configuration in the factory.py file or
-         export an FLASKR_SETTINGS environment variable
+         export a FLASKR_SETTINGS environment variable
          pointing to a configuration file or pass in a
          dictionary with config values using the create_app
          function.
@@ -19,7 +19,7 @@
 
          pip install --editable .
 
-      3. Instruct flask to use the right application
+      3. instruct flask to use the right application
 
          export FLASK_APP=flaskr.factory:create_app()