bug: USG recharge seepage elevation

[kbefus]

Describe the bug
USG recharge write function uses rech instead of selev variable to write selev array.

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Line 121 in mfusgrch'
2. See error: rech instead of selev

Additional context
I also had an error with not enough spaces between options and added a space before the # in the f_rch.write command to correct it, line 222.

flopy/flopy/mfusg/mfusgrch.py

Line 222 in 866bb58

f_rch.write("# Stress period {kper + 1}\n")

from f_rch.write(f"# Stress period {kper + 1}\n") to f_rch.write(f" # Stress period {kper + 1}\n")

[wpbonelli]

thanks for reporting @kbefus, this is fixed in develop.