Document dependency on nm
"""
This script confirms that the naming of all symbols and identifiers in Mbed TLS
-are consistent with the house style and are also self-consistent. It performs
-the following checks:
+are consistent with the house style and are also self-consistent. It only runs
+on Linux and macOS since it depends on nm.
+
+The script performs the following checks:
- All exported and available symbols in the library object files, are explicitly
- declared in the header files.
+ declared in the header files. This uses the nm command.
- All macros, constants, and identifiers (function names, struct names, etc)
follow the required pattern.
- Typo checking: All words that begin with MBED exist as macros or constants.
