Add note about XDG_DATA_HOME

[theferrit32]

May be overkill to add this but I did hit this and it took me a couple minutes to find out where it was coming from

[jsstevenson]

I think this might be better homed in the docs than in the README (the latter should ideally be more high level going forward)

[jsstevenson]

also a more limited fix would be to declare the WAGS_TAILS_DIR env variable: https://wags-tails.readthedocs.io/latest/usage.html#configuration . I think I should probably add some error handling in wags-tails to make it more visible where/why this is happening, maybe including a link to that doc entry ^

[theferrit32]

iterm2 on MacOS doesn't modify XDG_DATA_DIRS but for whatever reason ghostty which I am using now does set it if it is not set. So I modified my ~/.zprofile to set a value for XDG_DATA_HOME and XDG_DATA_DIRS because I think that ghostty thing could break other stuff too, potentially. I think we also discussed implementing this sort of XDG var usage for SEQREPO_ROOT_DIR defaults.

Maybe if you could enhance the wags-tails function to catch the permission error and include a link to that page. Then we can close this.

[jsstevenson]

@theferrit32 I have a draft remedy for the above + a few related concerns GenomicMedLab/wags-tails#79