Add a figure detailing the template elements

[jypeter]

@doutriaux1 I can't find the figure you sent me giving the name and location of the different elements of a template. Can you send it again, and add it to a relevant part of the vcs documentation?

And then you can probably link to it from around In [12] of https://cdat.llnl.gov/Jupyter/Basic_VCS_demo/Basic_VCS_demo.html

Thanks!

[jypeter]

@doutriaux1 ping. I have just worked a bit with Masa, and something helping us figure out where datanama/varname/title/etc... would have helped. I think we need to know both where these things are located by default and where they get their value from. Thanks!