Fix typos in steering_controllers_lib

[christophfroehlich]

Ackermann is a proper name and should be used as such.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.81%. Comparing base (2375aca) to head (d657ae6).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1464      +/-   ##
==========================================
- Coverage   83.83%   83.81%   -0.02%     
==========================================
  Files         122      122              
  Lines       11120    11122       +2     
  Branches      944      946       +2     
==========================================
  Hits         9322     9322              
  Misses       1489     1489              
- Partials      309      311       +2     

Flag	Coverage Δ
unittests	83.81% <100.00%> (-0.02%)	⬇️

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Files with missing lines	Coverage Δ
...g_controller/src/ackermann_steering_controller.cpp	80.00% <ø> (ø)
...roller/test/test_ackermann_steering_controller.hpp	86.59% <ø> (ø)
...ntroller/test/test_bicycle_steering_controller.hpp	83.11% <ø> (ø)
...llers_library/src/steering_controllers_library.cpp	79.72% <100.00%> (ø)
...library/test/test_steering_controllers_library.hpp	96.87% <ø> (ø)
...troller/test/test_tricycle_steering_controller.hpp	85.05% <ø> (ø)

... and 4 files with indirect coverage changes