This commit updates the screenshots in the user guide to reflect the
latest UI.
It also removes the links of video demos as they are based on earlier
builds.
Signed-off-by: Daniel Jiang <jiangd@vmware.com>
* update user guide
* update user guide
* update user guide
* update user guide
* update user guide
* fix refer
* update user guide gc
* update user guide
* update user guide
* update user guide
* update user guide