minor fix to crs doc-strings

[bjlittle]

Minor correction to crs doc-strings

[codecov]

Codecov Report

Merging #1004 (835f08b) into master (75b5d04) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1004   +/-   ##
=======================================
  Coverage   96.26%   96.26%           
=======================================
  Files          20       20           
  Lines        1767     1767           
=======================================
  Hits         1701     1701           
  Misses         66       66           

Impacted Files	Coverage Δ
pyproj/crs/crs.py	97.97% <ø> (ø)

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[snowman2]

Thanks!