Add man pages

[Archie-2021]

I am having a hard to finding the settings for this application. There is no guide , no man page and clipmenu --help is only few lines,

1. I am not sure where the override file would be created with systemctl --user edit clipmenud
2. Where should I specify in the setting to
   a. Exclude the primary clipboard
   b. To exclude the pass program as mentioned in the ReadMe.

Thanks for this awesome program. Dmenu is my favorite program and this program is one of the best ones based on the Dmenu.

[cdown]

Sorry I missed this! man pages are likely to come with clipmenu 7, and I'll keep this open until that happens.