Without further ado, the following was found:

Issue:    Documentation/filesystems/sharedsubtree.txt → Documentation/filesystems/sharedsubtree.rst

"For a discussion of propagation types when moving mounts (B<MS_MOVE>)  and "
"creating bind mounts (B<MS_BIND>), see I<Documentation/filesystems/"
"sharedsubtree.txt>."

"I<Documentation/filesystems/sharedsubtree.txt> in the kernel source tree."