consider using validate-element-name package

[btopro]

#53 came up in some UX testing with a new developer running init but just last week when I had a similar issue I came across a package called validate-element-name - https://www.npmjs.com/package/validate-element-name

This would include valid feedback as to the specific issue in question with what someone enters but what I also noted with it is that they also have additional checks in that I previously have not considered as they are going off the spec -- https://html.spec.whatwg.org/multipage/scripting.html#valid-custom-element-name

This has additional names of elements that are not valid because of conflicts with the name space used elsewhere in the web platform.

If there is interest in adding support for this to match the spec I'd be happy to assign this to a student to work into open-wc this semester.