config doc: fix reference to config.worktree info

356aea6 ("doc: move extensions.worktreeConfig to the right place",
2018-11-14) moved the explanation of extension.worktreeConfig from
config.txt to technical/repository-version.txt. However, the former
still contains a reference to the removed paragraph. We could fix it
referencing the gitrepository-layout man page, which contains the moved
explanation. But the git-worktree man page has additional information
and recommendations for the worktree config file, so let's reference it
instead.

Signed-off-by: Matheus Tavares <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: matheustavares

Documentation/config.txt

@@ -3,11 +3,12 @@ CONFIGURATION FILE
 
 The Git configuration file contains a number of variables that affect
 the Git commands' behavior. The files `.git/config` and optionally
-`config.worktree` (see `extensions.worktreeConfig` below) in each
-repository are used to store the configuration for that repository, and
-`$HOME/.gitconfig` is used to store a per-user configuration as
-fallback values for the `.git/config` file. The file `/etc/gitconfig`
-can be used to store a system-wide default configuration.
+`config.worktree` (see the "CONFIGURATION FILE" section of
+linkgit:git-worktree[1]) in each repository are used to store the
+configuration for that repository, and `$HOME/.gitconfig` is used to
+store a per-user configuration as fallback values for the `.git/config`
+file. The file `/etc/gitconfig` can be used to store a system-wide
+default configuration.
 
 The configuration variables are used by both the Git plumbing
 and the porcelains. The variables are divided into sections, wherein