Fix default values doc for min-worker-lifetime & legion-skew-tolerance

[thomas-riccardi]

I reviewed all options that mention default in their help string and found these two discrepancies.

sources:

• https://github.com/unbit/uwsgi/blob/ee46b79a4fe31d0a7f5056bf9db3aff01051e064/core/init.c#L140-L141
• https://github.com/unbit/uwsgi/blob/ee46b79a4fe31d0a7f5056bf9db3aff01051e064/core/legion.c#L492-L493

[xrmx]

Good catch!