Doc: <lilypond> is a tag not an environment

[Federico Bruni]

Hi

While translating I saw that the <lilypond> tag recognized by 
lilypond-book is called environment (as \lilypond{} in LaTeX).
Wouldn't it be more correct to call it tag?

Here's the part of the Usage manual where HTML is discussed:
https://gitlab.com/lilypond/lilypond/-/blob/master/Documentation/en/usage/lilypond-book.itely#L562

I hate these nitpicks :-)