docs: update info command for newer PyVISA

[Jayman2000]

In PyVISA’s repo, fcd3728 (updated commands to pyvisa-shell and pyvisa-info, 2017-11-22) replaced

python -m visa

with the pyvisa-shell and pyvisa-info commands. At this point, you have to use pyvisa-info. Running

python -m visa info

will no longer work.

---

• [ ] Closes # (insert issue number if relevant)

• [ ] Executed black . && isort -c . && flake8 with no errors: Here’s the output, but I don’t think that it’s relevant to my PR:

  black . && isort -c . && flake8
  All done! ✨ 🍰 ✨
  22 files left unchanged.
  ERROR: /hdd/home/jayman/VC/Partially mine/pyvisa-py/repo/docs/source/conf.py Imports are incorrectly sorted and/or formatted.
  Skipped 2 files

• [ ] The change is fully covered by automated unit tests

• [x] Documented in docs/ as appropriate

• [ ] Added an entry to the CHANGES file: I didn’t add one because I didn’t see any docs changes in the CHANGES file.

[MatthieuDartiailh]

Thanks