docs: add link

[`template`
action](https://pkg.go.dev/text/template#hdr-Actions)

assets/chezmoi.io/docs/user-guide/manage-machine-to-machine-differences.md

@@ -153,12 +153,12 @@ If you want to have the same file contents in different locations on different
 systems, but maintain only a single file in your source state, you can use a
 shared template.
 
-Create the common file in the `.chezmoitemplates` directory in the source
-state. For example, create `.chezmoitemplates/file.conf`. The contents of this
-file are available in templates with the `template $NAME .` function where
-`$NAME` is the name of the file (`.` passes the current data to the template
-code in `file.conf`; see https://pkg.go.dev/text/template#hdr-Actions for
-details).
+Create the common file in the `.chezmoitemplates` directory in the source state.
+For example, create `.chezmoitemplates/file.conf`. The contents of this file are
+available in templates with the `template $NAME .` function where `$NAME` is the
+name of the file (`.` passes the current data to the template code in
+`file.conf`; see [`template`
+action](https://pkg.go.dev/text/template#hdr-Actions) for details).
 
 Then create files for each system, for example `Library/Application
 Support/App/file.conf.tmpl` for macOS and `dot_config/app/file.conf.tmpl` for