[July 22, 2021] Add citation instructions (#20194)

* Add citation instructions

* Add citation to index (toc)

* Add citation intro

* Change toc position

* Tweak wording

* Mention citation in about readme

* Update based on suggestions

* Address feedback for CITATION

* One more code backticks for file name

* Apply suggestions from code review

* Rename file and add image

* Add conditions for different versions

* Adds example Citation.cff

* Update content/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-citation-files.md

* Update content/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-citation-files.md

* Improve CITATION.cff example

Co-authored-by: Arfon Smith <arfon@users.noreply.github.com>

* Update GHES & GHAE versions

* Fixing whitespace

Co-authored-by: Felicity Chapman <felicitymay@github.com>
Co-authored-by: Emma Makinson <emmaviolet@github.com>
Co-authored-by: Arfon Smith <arfon@users.noreply.github.com>
Co-authored-by: Emily Gould <4822039+emilyistoofunky@users.noreply.github.com>

content/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-citation-files.md

@@ -0,0 +1,43 @@
+---
+title: About CITATION files
+intro: 'You can add a CITATION file to your repository to help users correctly cite your software.'
+versions:
+  fpt: '*'
+  ghes: '>=3.3'
+  ghae: '>=M3'
+topics:
+  - Repositories
+---
+## About CITATION files
+
+You can add a `CITATION.cff` file to the root of a repository to let others know how you would like them to cite your work. The citation file format is plain text with human- and machine-readable citation information. 
+
+Example CITATION.cff:
+```
+cff-version: 1.2.0
+message: "If you use this software, please cite it as below."
+authors:
+- family-names: Lisa
+  given-names: Mona
+  orcid: https://orcid.org/0000-0000-0000-0000
+- family-names: Bot
+  given-names: Hew
+  orcid: https://orcid.org/0000-0000-0000-0000
+title: "My Research Software"
+version: 2.0.4
+doi: 10.5281/zenodo.1234
+date-released: 2017-12-18
+url: https://github.com/github/linguist
+```
+
+For more information, see the [Citation File Format](https://citation-file-format.github.io/) website.
+
+When you add a `CITATION.cff` file to the default branch of your repository, it is automatically linked from the repository landing page. This makes it easy for other users to cite your software project, using the information you've provided.
+
+![Citation link on repository landing page](/assets/images/help/repository/citation-link.png)
+
+## Citation formats
+
+We currently support APA and BibTex file formats.
+
+Are you looking for additional citation formats? GitHub uses a Ruby library, to parse the `CITATION.cff` files. You can request additional formats in the [ruby-cff](https://github.com/citation-file-format/ruby-cff) repository, or contribute them yourself.

content/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/about-readmes.md

@@ -15,7 +15,7 @@ topics:
 ---
 ## About READMEs
 
-You can add a README file to a repository to communicate important information about your project. A README, along with a repository license{% ifversion fpt %}, contribution guidelines, and a code of conduct{% elsif ghes %} and contribution guidelines{% endif %}, communicates expectations for your project and helps you manage contributions.
+You can add a README file to a repository to communicate important information about your project. A README, along with a repository license{% ifversion fpt or ghes > 3.1 or ghae-issue-4651 %}, citation file{% endif %}{% ifversion fpt %}, contribution guidelines, and a code of conduct{% elsif ghes %} and contribution guidelines{% endif %}, communicates expectations for your project and helps you manage contributions.
 
 For more information about providing guidelines for your project, see {% ifversion fpt %}"[Adding a code of conduct to your project](/communities/setting-up-your-project-for-healthy-contributions/adding-a-code-of-conduct-to-your-project)" and {% endif %}"[Setting up your project for healthy contributions](/communities/setting-up-your-project-for-healthy-contributions)."
 

content/github/creating-cloning-and-archiving-repositories/creating-a-repository-on-github/index.md

@@ -18,6 +18,7 @@ children:
   - /about-code-owners
   - /about-repository-languages
   - /licensing-a-repository
+  - /about-citation-files
   - /creating-a-template-repository
   - /creating-an-issues-only-repository
   - /limits-for-viewing-content-and-diffs-in-a-repository