docs: use code-tag instead of pre-tag

docs: use code-tag instead of pre-tag

It's unlikely the author meant to use <pre>-here, as that starts a whole
new block. Instead, the inline code-tag seems more appropriate here.

Fixes: 41b3eb08d9f "docs: update meson docs for windows"
Acked-by: Dylan Baker <dylan@pnwbakers.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3431>