Readme is missing comparelibs.py

[DanSGiesbrecht]

I noticed that the readme.md is missing a description for comparelibs.py.

[poeschlr]

As an inspiration: Running it with --help gives the following:
Additional info: This script is what is used to run travis checks only on the symbols that have been changed by the contribution.

usage: comparelibs.py [-h] [--new NEW [NEW ...]] [--old OLD [OLD ...]] [-v]
                      [--check] [--nocolor] [--design-breaking-changes]
                      [--check-aliases] [--shownochanges]

Compare two .lib files to determine which symbols have changed

optional arguments:
  -h, --help            show this help message and exit
  --new NEW [NEW ...]   New (updated) .lib file(s)
  --old OLD [OLD ...]   Old (original) .lib file(s) for comparison
  -v, --verbose         Enable extra verbose output
  --check               Perform KLC check on updated/added components
  --nocolor             Does not use colors to show the output
  --design-breaking-changes
                        Checks if there have been changes made that would
                        break existing designs using a particular symbol.
  --check-aliases       Do not only check symbols but also aliases.
  --shownochanges       Show libraries that have not changed