Fixed two typos in Control Panel section of User Guide
LRDOCS-408 Updated the Control Panel section of the User Guide with info on the *Clear the direct servlet cache* option and the *Reindex all spell check indexes* options
LRDOCS-408 Added more information to the User Guide on the options for clearing caches from the Control Panel
Merge pull request #435 from jrao/LRDOCS-408

https://issues.liferay.com/browse/LRDOCS-408