Adding the FAQ back

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)

docs/mkdocs.yml

@@ -95,6 +95,7 @@ pages:
 - ['reference/commandline/index.md', '**HIDDEN**']
 - ['reference/commandline/cli.md', 'Reference', 'Command line']
 - ['reference/builder.md', 'Reference', 'Dockerfile']
+- ['faq.md', 'Reference', 'FAQ']
 - ['reference/run.md', 'Reference', 'Run Reference']
 - ['articles/index.md', '**HIDDEN**']
 - ['articles/runmetrics.md', 'Reference', 'Runtime metrics']