The reference menu is too big to list more than the latest API docs, so the others can be hidden - they're still linked from the API summary

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

docs/mkdocs.yml

@@ -121,11 +121,11 @@ pages:
 - ['reference/api/docker_remote_api.md', 'Reference', 'Docker Remote API']
 - ['reference/api/docker_remote_api_v1.17.md', 'Reference', 'Docker Remote API v1.17']
 - ['reference/api/docker_remote_api_v1.16.md', 'Reference', 'Docker Remote API v1.16']
-- ['reference/api/docker_remote_api_v1.15.md', 'Reference', 'Docker Remote API v1.15']
-- ['reference/api/docker_remote_api_v1.14.md', 'Reference', 'Docker Remote API v1.14']
-- ['reference/api/docker_remote_api_v1.13.md', 'Reference', 'Docker Remote API v1.13']
-- ['reference/api/docker_remote_api_v1.12.md', 'Reference', 'Docker Remote API v1.12']
-- ['reference/api/docker_remote_api_v1.11.md', 'Reference', 'Docker Remote API v1.11']
+- ['reference/api/docker_remote_api_v1.15.md', '**HIDDEN**']
+- ['reference/api/docker_remote_api_v1.14.md', '**HIDDEN**']
+- ['reference/api/docker_remote_api_v1.13.md', '**HIDDEN**']
+- ['reference/api/docker_remote_api_v1.12.md', '**HIDDEN**']
+- ['reference/api/docker_remote_api_v1.11.md', '**HIDDEN**']
 - ['reference/api/docker_remote_api_v1.10.md', '**HIDDEN**']
 - ['reference/api/docker_remote_api_v1.9.md', '**HIDDEN**']
 - ['reference/api/docker_remote_api_v1.8.md', '**HIDDEN**']