tutorial: disable section anchor links

[nycki93]

the default behavior of phantomake when encountering a markdown "header" such as this:

## getting started

is to rewrite it as a linked anchor:

<h2 id="getting-started"><a href="#getting-started">getting started</a></h2>

if you want to disable this behavior, add this to your css:

h1 a, h2 a, h3 a, h4 a, h5 a, h6 a {
  all: unset;
  pointer-events: none;
}

this will make the header render as normal non-clickable text, but anchor links that point at the header will still work.