docs: fix an example about how to write Pandas.DataFrame

[bednar]

Related to a1f9826#r47111313

Proposed Changes

Fixed an example about how to write Pandas.DataFrame

Checklist

• Rebased/mergeable
• pytest tests completes successfully
• Commit messages are in semantic format
• Sign CLA (if not already signed)

[codecov]

Codecov Report

Merging #196 (deea4b4) into master (d396581) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #196   +/-   ##
=======================================
  Coverage   89.88%   89.88%           
=======================================
  Files          26       26           
  Lines        1967     1967           
=======================================
  Hits         1768     1768           
  Misses        199      199           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d396581...deea4b4. Read the comment docs.

[bednar]

Also "now" doesn't exist, l.332 defines _now

Fixed