[AIRFLOW-XXX] Fix typos in faq.rst (#3837)

Author: XD-DENG

docs/faq.rst

@@ -141,15 +141,15 @@ What are all the ``airflow run`` commands in my process list?
 There are many layers of ``airflow run`` commands, meaning it can call itself.
 
 - Basic ``airflow run``: fires up an executor, and tell it to run an
-  ``airflow run --local`` command. if using Celery, this means it puts a
-  command in the queue for it to run remote, on the worker. If using
+  ``airflow run --local`` command. If using Celery, this means it puts a
+  command in the queue for it to run remotely on the worker. If using
   LocalExecutor, that translates into running it in a subprocess pool.
 - Local ``airflow run --local``: starts an ``airflow run --raw``
   command (described below) as a subprocess and is in charge of
   emitting heartbeats, listening for external kill signals
-  and ensures some cleanup takes place if the subprocess fails
+  and ensures some cleanup takes place if the subprocess fails.
 - Raw ``airflow run --raw`` runs the actual operator's execute method and
-  performs the actual work
+  performs the actual work.
 
 
 How can my airflow dag run faster?