Add videos for admins to docs

@fernandinand created videos for admins on this folder: https://drive.google.com/drive/folders/1Xo2x7uHR5JYWjH3a3gZp7HAwlNTE2WQ6?usp=drive_link

We need to 
1/ Diana or/and @VitorVieiraZ to add beginning and end to videos and upload it to our YouTube Channel in separate playlist for Mergin Maps Server Administrators
2/ Add the links to the docs (@fernandinand or @alex-cit ?)

