docs: add missing backticks

Author: paulhdk

clang-tools-extra/docs/clang-tidy/checks/cppcoreguidelines/pro-bounds-avoid-unchecked-container-access.rst

@@ -25,7 +25,8 @@ and
 
 will generate a warning.
 
-STL containers for which operator[] is well-defined for all inputs are excluded from this check (e.g.: std::map::operator[]).
+STL containers for which operator[] is well-defined for all inputs are excluded
+from this check (e.g.: ``std::map::operator[]``).
 
 This check enforces part of the `SL.con.3
 <https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#slcon3-avoid-bounds-errors>`