Document Manager; File Category is now better validated

Document Manager Files have the ability to include a Category. The Category is now better validated so invalid characters like a colon ":" are not allowed.

The valid characters include:

• A-Z
• a-z
• 0-9
• space
• _ underscore
• - dash
• . full stop

Note, Categories relate to the sub-folder a file is saved in within the File System. This means folders may break the list of valid characters noted above if they are created via Windows File Explorer.