Documentation/gitpacking: make sample configs listing blocks

This document contains a few sample config snippets. At least with
Asciidoctor, the section headers are rendered *more* indented than the
variables that follow:

       [bitmapPseudoMerge "all"]
    pattern = "refs/"
    ...

To address this, wrap these listings in AsciiDoc listing blocks. Remove
the indentation from the section headings. This is similar to how we
handle such sample config elsewhere, e.g., in config.txt.

While we're here, fix the nearby "wiht" typo.

Signed-off-by: Martin Ågren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Martin Ågren

Documentation/gitpacking.txt

@@ -143,14 +143,16 @@ include::config/bitmap-pseudo-merge.txt[]
 Suppose that you have a repository with a large number of references,
 and you want a bare-bones configuration of pseudo-merge bitmaps that
 will enhance bitmap coverage of the `refs/` namespace. You may start
-wiht a configuration like so:
+with a configuration like so:
 
-    [bitmapPseudoMerge "all"]
+----
+[bitmapPseudoMerge "all"]
 	pattern = "refs/"
 	threshold = now
 	stableThreshold = never
 	sampleRate = 100
 	maxMerges = 64
+----
 
 This will create pseudo-merge bitmaps for all references, regardless of
 their age, and group them into 64 pseudo-merge commits.
@@ -159,21 +161,25 @@ If you wanted to separate tags from branches when generating
 pseudo-merge commits, you would instead define the pattern with a
 capture group, like so:
 
-    [bitmapPseudoMerge "all"]
+----
+[bitmapPseudoMerge "all"]
 	pattern = "refs/(heads/tags)/"
+----
 
 Suppose instead that you are working in a fork-network repository, with
 each fork specified by some numeric ID, and whose refs reside in
 `refs/virtual/NNN/` (where `NNN` is the numeric ID corresponding to some
 fork) in the network. In this instance, you may instead write something
 like:
 
-    [bitmapPseudoMerge "all"]
+----
+[bitmapPseudoMerge "all"]
 	pattern = "refs/virtual/([0-9]+)/(heads|tags)/"
 	threshold = now
 	stableThreshold = never
 	sampleRate = 100
 	maxMerges = 64
+----
 
 Which would generate pseudo-merge group identifiers like "1234-heads",
 and "5678-tags" (for branches in fork "1234", and tags in remote "5678",