TOUGH2 Examples

[softwareengineerprogrammer]

Added Examples 6 & 7 per yesterday's sync.

1. example6.txt was taken from GEOPHIRES-v2's example6.txt. Case report generated by Abra.
2. example7.txt was provided by @kfbeckers - it is identical to example 6 except that it has a single gradient instead of multiple gradients. Case report generated by Abra.
3. Edited both examples' description for accuracy (they incorrectly claimed they were using BICYCLE model but actually use Standard LCOE/LCOH model)
4. Disabled examples from running in tests (necessary until we solve for obtaining/supporting TOUGH model in GitHub Actions/dev machines), referenced tracking issue: TOUGH test support: TOUGH test support #318
5. Updated README:

TOUGH2 web interface support tracking issue: softwareengineerprogrammer/geothermal-ui#15