Refer #15 and expand on the CLI section of Stencil docs making it more comprehensive.
Add the following information:

• Information around what stencil-cli is
• Information around what stencil-cli is capable of
• Information on how to install stencil-cli
• Information on the supported features
• Comprehensive documentation on the capabilities of each feature
• Section on known bugs and their documentation

NOTE: The above list is not an esxhaustive list and will keep getting updated as we keep getting more feedback.