Update developer guide

[Rahul-D78]

Currently the developer guide only has information about Building and Installing kubeslice-worker and how to run tests. It should also include:

• Guidelines for submitting a pull request.
• Commit Message Guidelines like PR should have a description body and a proper commit prefix.
• Coding Rule section can include topics like following the GoLang style guide, Unit tests and Integration tests as well as adding comments in the code.
• Commit prefix can be one of the type.

  build: Changes that affect the build system or external dependencies (example scopes: Makefile, Dockerfile)
  ci: Changes to our CI configuration files and scripts (example scopes: GitHub Action, JenkinsFile)
  docs: Documentation only changes
  feat: A new feature
  fix: A bug fix
  perf: A code change that improves performance
  refactor: A code change that neither fixes a bug nor adds a feature
  style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
  test: Adding missing tests or correcting existing tests

[narmidm]

@Rahul-D78 - recreate this with the issue with the bug template for better visibility. After that please close the issue.

[Rahul-D78]

Changes are already present - https://github.com/kubeslice/worker-operator/blob/master/CONTRIBUTING.md