fixes small typos in CHANGES.md

[NicholasWilsonDEV]

I really enjoyed using this project, nice work! Found a couple of typos in the CHANGES though 😛

Thanks for making a pull request to converse.js!

Before submitting your request, please make sure the following conditions are met:

• [x] Add a changelog entry for your change in CHANGES.md
• [ ] When adding a configuration variable, please make sure to document it in docs/source/configuration.rst
• [ ] Please add a test for your change. Tests can be run in the commandline with make check or you can run them in the browser by running make serve and then opening http://localhost:8000/tests.html.