docs: Added all-contributions instructions closes #204

[AlexanderTheGrape]

• [ ] The pull request is complete according to the following criteria:
  • [ ] Acceptance criteria have been met
  • [x] The documentation is kept up-to-date
  • [ ] Comprehensive tests (if applicable) have been generated and all pass.
  • [ ] The pull request describes the changes that have been made, and enough information is present in the description for any developer to understand what has changed
  • [ ] Commits have been squashed (or will be on merge).
  • [ ] The branch name is descriptive and follows the pull request title format : {issue/bug...}/(Issue Number) - Name of issue. E.g bug/30-Fix-Project
  • [ ] The pull request title is of the following format : {issue/bug...}/(Issue Number) - Name of issue. E.g bug/30-Fix-Project
  • [ ] The description uses github syntax to link to the issue. E,g Resolves se701g2/Doto#{Number}
  • [x] At least two reviewers assigned. One of which must be the assigner of the issue.
  • [ ] If there are merge conflicts, run git rebase as opposed to git merge with master.

[AlexanderTheGrape]

Note that this pull request is tied to this pull request https://github.com/se701g2/Doto/pull/266 which must be merged first before closing the issue https://github.com/se701g2/Doto/issues/204