Update parametric_ops.py documentation

[KetpuntoG]

typo in the documentation

[github-actions]

Hello. You may have forgotten to update the changelog!
Please edit doc/releases/changelog-dev.md with:

• A one-to-two sentence description of the change. You may include a small working example for new features.
• A link back to this PR.
• Your name (or GitHub username) in the contributors section.

[codecov]

Codecov Report

Merging #3676 (40415e7) into master (d4a3de1) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3676   +/-   ##
=======================================
  Coverage   99.76%   99.76%           
=======================================
  Files         319      319           
  Lines       28260    28260           
=======================================
  Hits        28194    28194           
  Misses         66       66           

Impacted Files	Coverage Δ
pennylane/ops/qubit/parametric_ops.py	99.90% <ø> (ø)

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[rmoyard]

Great catch thanks! 👍