TrkSurfaces: Fix typo in comments.

Fix typo in comments.

This merge request affects 1 package:

• Tracking/TrkDetDescr/TrkSurfaces

added Tracking master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-24857-2019-07-13-02-41
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 1125]

added review-approved label

removed review-pending-level-1 label

merged

mentioned in commit 54ebedd9

added sweep:ignore label