Add CNCF Branding Elements Near Bottom of Page

[nate-double-u]

As per the CNCF Website Guidelines, add the following to the footer (or somewhere near the bottom of the page):

• “We are a Cloud Native Computing Foundation sandbox project.”
  This can change depending on the status of the project, but I expect most of the users of this template will be in the sanbox.
• CNCF logo
• Link to KubeCon + CloudNativeCon.
  This is optional, but a sample of placement may be valuable.