Remove the marketing information from the README md file, put back IntelliJ SVG logo in the credit section

AC1:
Use the original OSS logo, description text.
Raise a PR to remove the marketing images of Zerocode Ltd, information text from the README file, and elsewhere available as tidyup tasks

AC2:
Put the JetBrains IntelliJ credit SVG image for their free IDE licenses to the developers to the README file and elsewhere available

AC3:
Test key validity or get it reissued