Adopt @ldionne's clarification for comments

Co-authored-by: Louis Dionne <[email protected]>

Author: frederick-vs-ja

libcxx/test/libcxx/numerics/complex.number/cmplx.over.pow.pass.cpp

@@ -14,7 +14,9 @@
 
 // Test that these additional overloads are free from catching std::complex<non-floating-point>,
 // which is expected by several 3rd party libraries, see https://github.com/llvm/llvm-project/issues/109858.
-
+//
+// Note that we reserve the right to break this in the future if we have a reason to, but for the time being,
+// make sure we don't break this property unintentionally.
 #include <cassert>
 #include <cmath>
 #include <complex>