LU-18687 doc: move man pages to Documentation [0]

LU-18687 doc: move man pages to Documentation [0]

Consolidate all of the man pages into the top
level Documentation directory.

Start by setting up the initial directory
structure in Documentation/.

Test-Parameters: trivial
Signed-off-by: Timothy Day <timday@amazon.com>
Change-Id: I15ed0687803513a7726cc5bd53b5ee5eb8f699f0
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58021
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Ellis Wilson <elliswilson@microsoft.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>