Update extensions.md

follow up commit (apologies for submiting these to master, not through a PR - I did the first one by mistake and this one is a follow up.

docs/documentation/extensions.md

@@ -86,16 +86,17 @@ With this option you have a very small README file and a separate MkDocs guide w
 
 Add some [markdown](/documentation/markdown.md) content in `docs/index.md`.
 
-## Preview your guide
-
-Now you should be able to run `mkdocs serve` from within your project directory to start previewing your content. See [instructions here](/documentation/index.md#mkdocs) to get MkDocs set up.
-
 You can add more pages by creating more markdown files and specifying these files under `pages` in `mkdocs.yml`.
 
 !!! note
     We have [markdown coding standards](/documentation/markdown.md#standards) and a documentation [style guide](/documentation/style-guide.md). Adherence to these rules within your extensions docs is recommended but not required.
 
 
+## Preview your guide
+
+Now you should be able to run `mkdocs serve` from within your project directory to start previewing your content. See [instructions here](/documentation/index.md#mkdocs) to get MkDocs set up.
+
+
 ## Submit your guide to our publishing system {:#submit}
 
 Once your guide is in good shape it's time to get it up on [docs.civicrm.org](https://docs.civicrm.org).