Update `README.md` to reflect changes in `v1.0.0`

Currently the logo within the `README.md` is using a website version of the `CodeEntropy` logo hosted from the [CCPBioSim branding GitHub](https://github.com/CCPBioSim/branding), this leads to the `CodeEntropy` GitHub website not being able to load the logo effectivly. This should be changed to the logo that is located within `CodeEntropy/docs/images`.