doc/gnatcov: remove documentation of limitation

This limitation was removed with enhanced support for macros.

Change-Id: I1d68baa2f1c7ca86893d3934e3be76d2b1b6c9ef
TN: V426-009

Author: Jugst3r

doc/gnatcov/src_traces.rst

@@ -507,13 +507,6 @@ And to instrument Ada, C and C++ units:
 
    gnatcov instrument --restricted-to-languages=Ada,C,C++ # ...
 
-Instrumentation and coverage of C/C++ code
-==========================================
-
-Instrumentation operates on the preprocessed code, which means that coverage
-obligations that come from a macro expansion (and further obligations on the
-same line) will have inaccurate column numbers.
-
 .. _spark_instr :
 
 Instrumentation and coverage of SPARK code