Mostly based on recent language decisions from "everything curl":
- remove contractions (isn't => is not)
- *an* HTTP (consistency)
- runtime (no hyphen)
- backend (no hyphen)
- URL is uppercase
Closes#8646
Make all libcurl related options use .nf (no fill) for the SYNOPSIS
section - for consistent look. roffit then renders that section using
<pre> (monospace font) in html for the website.
Extended manpage-syntax (test 1173) with a basic check for it.
Closes#8062