Have the right anchors in documentation to help search engines

[ViralBShah]

For example, when you google "julia kron doc", it sends you to the LinearAlgebra documentation at https://docs.julialang.org/en/v1/stdlib/LinearAlgebra/. If possible, we should have the right anchors on the page so that search engines can send you directly to the relevant section on that page.

cc @Keno @StefanKarpinski

[mortenpi]

Hmm. We put the name of each of the docstrings in a <header> tag (inside the <article> container of each docstrings), whereas maybe we should use <h1> instead (based on looking at mdn for <article> and <header>).

[MarkNahabedian]

Would leaving a name anchor, e.g. <a name="fragment"/> help here?

[mortenpi]

Looking at the docs, the name attribute looks to be the same as id and seems to be pretty much deprecated. And we already have anchors with ids:

I still think that using a proper heading, instead of the <header> tag, should promote this for the search engines.