Add documentation for Bitrise integration

[pascalberger]

We should add documentation for the Bitrise integration in https://cakebuild.net/docs/build-systems/. See https://github.com/cake-build/bitrise-cake-step

[Abhishekchauhan089]

i would like to work on this issue

[pascalberger]

The Bitrise step is available at https://www.bitrise.io/integrations/steps/cakebuild and source code at https://github.com/cake-build/bitrise-cake-step. Scope of this issue is to add a new page at https://cakebuild.net/docs/build-systems/bitrise which documents how to install and use the bitrise step to run Cake builds on Bitrise (similar as done for Azure DevOps here: https://cakebuild.net/docs/build-systems/azure-devops).

@Abhishekchauhan089 Please let me know if you're interested in working on this