docs: Move manpages to separate toplevel

I belatedly noticed that the previous change effectively
"corrupted" the docs site by trying to include these generated
man pages.

I think we can figure out how to integrate them better, but
for now move them to a separate toplevel.

While we're here add one link from the main docs to the manpages.

Signed-off-by: Colin Walters <[email protected]>

Author: cgwalters

docs/index.md

@@ -99,7 +99,7 @@ installer that can set a system up to boot from it.  Crucially, if you create a
 *derivative* container image from a stock OS container image, it also automatically
 supports `bootc install`.
 
-For more information, please see [install.md](install.md).
+For more information, please see [install.md](install.md) as well as the [../manpages-md/bootc-install.md] manpage.
 
 #### Switching from an existing ostree-based system