Fix typos.

[bangerth]

Follow-up to #264.

[codecov]

Codecov Report

Merging #325 (6e0e183) into master (c90d631) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #325   +/-   ##
=======================================
  Coverage   98.90%   98.90%           
=======================================
  Files          75       75           
  Lines        4277     4277           
=======================================
  Hits         4230     4230           
  Misses         47       47           

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[github-actions]

Benchmark	Master	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.327 ± 0.052 (s=357)	1.329 ± 0.054 (s=323)	-0.9% .. +1.1%
Slab interpolation curved simple none	1.454 ± 0.009 (s=308)	1.451 ± 0.007 (s=314)	-0.3% .. -0.0%
Spherical slab interpolation simple none	1.519 ± 0.086 (s=337)	1.513 ± 0.088 (s=259)	-2.0% .. +1.1%
Slab interpolation simple curved CMS	1.600 ± 0.093 (s=287)	1.593 ± 0.088 (s=279)	-2.0% .. +1.1%
Spherical slab interpolation simple CMS	2.586 ± 0.039 (s=163)	2.593 ± 0.043 (s=187)	-0.3% .. +0.8%
Spherical fault interpolation simple none	1.443 ± 0.005 (s=300)	1.442 ± 0.004 (s=326)	-0.2% .. +0.0%

[MFraters]

Thanks!