fix some spelling mistakes in doc/

I check all the files under doc/ directory and find three
spelling mistakes
 - exeuction should be execution
 - Fefora should be Fedora
 - opentackclient should be openstackclient

Change-Id: If9e5d07b6558871bb3f8d55b52bf8f1d9db0897e

Author: JianqingJiang

doc/source/commands.rst

@@ -191,7 +191,7 @@ list check out :doc:`plugin-commands`.
 * ``stack resource``: (**Orchestration (Heat)**)
 * ``stack snapshot``: (**Orchestration (Heat)**)
 * ``stack template``: (**Orchestration (Heat)**)
-* ``task exeuction``: (**Workflow Engine (Mistral)**)
+* ``task execution``: (**Workflow Engine (Mistral)**)
 * ``tld``: (**DNS (Designate)**)
 * ``workbook``: (**Workflow Engine (Mistral)**)
 * ``workflow``: (**Workflow Engine (Mistral)**)

doc/source/developing.rst

@@ -30,7 +30,7 @@ Install the prerequisites for Tox:
   You may need to use pip install for some packages.
 
 
-* On RHEL or CentOS including Fefora:
+* On RHEL or CentOS including Fedora:
 
   .. code-block:: bash
 
@@ -103,7 +103,7 @@ only want to run the test that hits your breakpoint:
 
 .. code-block:: bash
 
-    $ tox -e debug opentackclient.tests.identity.v3.test_group
+    $ tox -e debug openstackclient.tests.identity.v3.test_group
 
 For reference, the `debug`_ ``tox`` environment implements the instructions