Adds documentation for community supported platforms

Add instructions for community maintained packages.

Ref : Github issue #5332

@jin Is this how you want it?

Closes #5582.

PiperOrigin-RevId: 204919383

site/docs/install.md

diff --git a/site/docs/install.md b/site/docs/install.md
index 6438657..ed85f14 100644
--- a/site/docs/install.md
+++ b/site/docs/install.md
@@ -12,4 +12,14 @@
 *   [macOS](install-os-x.md)
 *   [Windows](install-windows.md)
 
+## Community-Supported Packages
+*   [Arch Linux](https://www.archlinux.org/packages/community/x86_64/bazel/)
+*   [Gentoo](https://packages.gentoo.org/packages/dev-util/bazel)
+*   [Linuxbrew](https://github.com/Linuxbrew/homebrew-core/blob/master/Formula/bazel.rb)
+*   [Scoop](https://github.com/lukesampson/scoop/blob/master/bucket/bazel.json)
+*   [Nixpkgs](https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/build-managers/bazel/default.nix)
+*   [Parabola](https://www.parabola.nu/packages/?q=bazel)
+*   [FreeBSD](Ports: https://www.freshports.org/devel/bazel)
+
+
 For other platforms, you can try to [compile from source](install-compile-source.md).