`stockpiles` plugin shares name with DFHack tool tag

[Bumber64]

The stockpiles plugin shares a name with the stockpiles DFHack tool help tag. When clicking on the "?" button on the plugin's GUI, it shows the documentation for the plugin, but also sets the filter to tools with the stockpiles tag.

One of these should probably be changed. It seems easiest to just change the tag to stockpile.

[Bumber64]

I think the tag spreadsheet is also out of date. It's missing machine-toggle, gui/adv-finder, etc. Not sure how this is maintained, but it's linked on the Tags page.

https://docs.dfhack.org/en/latest/docs/tools/ in the spreadsheet should be https://docs.dfhack.org/en/latest/docs/Tools.html.