README encoding improvements ala #2070

[sydb]

Per #2070 step 2, change encoding of class names from <ident> (with or without type="class") to <name type="class">; and, in the case of 2.2.0 element names and class names from plain text to <gi> and <name type="class">, respectively. I did not fix any of the other individual problems noted in #2070 note [2], yet, but might get to it before this is merged. (None of those changes have to be done in conjunction with the changes here, but we should do them now lest we forget.)

WARNING
This PR cannot be considered in isolation, it must be combined with the corresponding PR in the Stylesheets repo.

[sydb]

In 29935ed I fixed most of the little things listed in note [2] on the ticket, #2070. I do not claim all errors are fixed, but I do claim that this branch is now significantly better than dev.