[Aug 24, 2021] Top level CLI docs set (#20628)

Co-authored-by: Ethan Palm <56270045+ethanpalm@users.noreply.github.com>
Co-authored-by: Mislav Marohnić <mislav@github.com>
Co-authored-by: Laura Coursen <lecoursen@github.com>

content/github-cli/github-cli/about-github-cli.md

@@ -0,0 +1,30 @@
+---
+title: About GitHub CLI
+intro: '{% data reusables.cli.cli-intro %}'
+versions:
+  fpt: '*'
+  ghes: '*'
+  ghae: '*'
+topics:
+  - CLI
+type: overview
+redirect_from:
+  - /github/getting-started-with-github/github-cli
+  - /github/getting-started-with-github/using-github/github-cli
+  - /actions/guides/managing-github-actions-with-github-cli
+---
+## About {% data variables.product.prodname_cli %}
+
+{% data reusables.cli.about-cli %}
+
+{% data reusables.cli.cli-features %}
+
+For more information about what you can do with {% data variables.product.prodname_cli %}, see the [{% data variables.product.prodname_cli %} manual](https://cli.github.com/manual).
+
+## Installing {% data variables.product.prodname_cli %}
+
+View installation instructions {% data variables.product.prodname_cli %} for macOS, Windows, and Linux on the [{% data variables.product.prodname_cli %} page](https://cli.github.com).
+
+## Sharing feedback
+
+If you have feedback or feature requests, you can open an issue in the [`cli/cli` repository](https://github.com/cli/cli).