asciidoctor: fix synopsis rendering (#5064)

Since 76880f0 (doc: git-clone: apply new documentation formatting
guidelines, 2024-03-29), the synopsis of `git clone`'s manual page is
rendered differently than before; Its parent commit did the same for
`git init`.

The result looks quite nice. When rendered with AsciiDoc, that is. When
rendered using AsciiDoctor, the result is quite unpleasant to my eye,
reading something like this:

	SYNOPSIS

	 git clone
	  [
	 --template=
	 <template-directory>]
		  [
	 -l
	 ] [
	 -s
	 ] [
	 --no-hardlinks
	 ] [
	 -q
	 ] [
	[... continuing like this ...]

Even on the Git home page, where AsciiDoctor's default stylesheet is not
used, this change results in some unpleasant rendering where not only
the font is changed for the `<code>` sections of the synopsis, but
padding and a different background color make the visual impression
quite uneven: compare https://git-scm.com/docs/git-clone/2.45.0 to
https://git-scm.com/docs/git-clone/2.44.0.

To fix this, let's apply the method recommended by AsciiDoctor in
https://docs.asciidoctor.org/asciidoctor/latest/html-backend/default-stylesheet/#customize-docinfo
to partially override AsciiDoctor's default style sheet so that the
`<code>` sections of the synopsis are no longer each rendered on their
own, individual lines.

This fixes #5063.

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Documentation/docinfo.html

@@ -0,0 +1,5 @@
+<style>
+pre>code {
+   display: inline;
+}
+</style>