[DOC]: To remove extra `` to match :class: rendering requirements

[uds5501]

Removing extra `` to solve rendering issues

• xref Tick DateOffset Normalize whatsnew entry has an error #21564
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

@TomAugspurger , I am not really much acquainted to :class: reference. Do tell me If I am wrong in the inference of the issue.
I guessed that the parameters should be enclosed in not `` by looking at the following:

pandas/doc/source/whatsnew/v0.24.0.txt

Lines 66 to 70 in f1ffc5f

	Datetimelike API Changes
	^^^^^^^^^^^^^^^^^^^^^^^^
	- For :class:`DatetimeIndex` and :class:`TimedeltaIndex` with non-``None`` ``freq`` attribute, addition or subtraction of integer-dtyped array or ``Index`` will return an object of the same class (:issue:`19959`)
	- :class:`DateOffset` objects are now immutable. Attempting to alter one of these will now raise ``AttributeError`` (:issue:`21341`)

[codecov]

Codecov Report

Merging #21586 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #21586      +/-   ##
==========================================
+ Coverage    91.9%    91.9%   +<.01%     
==========================================
  Files         153      153              
  Lines       49549    49549              
==========================================
+ Hits        45537    45539       +2     
+ Misses       4012     4010       -2

Flag	Coverage Δ
#multiple	90.3% <ø> (ø)	⬆️
#single	41.78% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/util/testing.py	85.27% <0%> (+0.2%)	⬆️

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[gfyoung]

That looks good!

cc @TomAugspurger @jreback

[jreback]

thanks, this only partially closes as for 2) in the issue.