docs: Fix a few typos

[timgates42]

There are small typos in:

• nose2/plugins/mp.py
• nose2/tests/functional/test_mp_plugin.py

Fixes:

• Should read pickleable rather than pickeable.
• Should read communicate rather than communciate.

Semi-automated pull request generated by https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

[sirosen]

Thanks!