Add dependabot ecosystem support for Rust toolchain (#56949)

Co-authored-by: mc <42146119+mchammer01@users.noreply.github.com>
Co-authored-by: Sophie <29382425+sophietheking@users.noreply.github.com>

Author: 3 people

content/code-security/dependabot/working-with-dependabot/dependabot-options-reference.md

@@ -503,6 +503,9 @@ Package manager | YAML value      | Supported versions |
 | pnpm   | `npm`            | v7, v8 <br>v9, v10 (version updates only)    |
 | poetry         | `pip`            | v2               |
 | pub         | `pub`            | v2  |
+| {% ifversion dependabot-rust-toolchain-support %} |
+| Rust toolchain | `rust-toolchain` | Not applicable   |
+| {% endif %} |
 | Swift   | `swift`      | v5  |
 | Terraform    | `terraform`      | >= 0.13, <= 1.10.x  |
 | uv           | `uv`             | v0 |

data/features/dependabot-rust-toolchain-support.yml

@@ -0,0 +1,6 @@
+# Reference: #19113
+# Rust toolchain support for Dependabot
+versions:
+  fpt: '*'
+  ghec: '*'
+  ghes: '>= 3.20'

data/reusables/dependabot/supported-package-managers.md

@@ -32,6 +32,9 @@ pipenv         | `pip`            | <= 2021-05-29    | {% octicon "check" aria-l
 | {% ifversion dependabot-updates-pnpmv9-support %}pnpm{% else %}[pnpm](#pnpm){% endif %}   | `npm`            | v7, v8, v9, v10      | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} {% ifversion dependabot-updates-pnpmv9-support %}{% else %}(v7 and v8 only){% endif %}| {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} |
 poetry         | `pip`            | v1               | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} |
 [pub](#pub)           | `pub`            | v2  | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} |
+| {% ifversion dependabot-rust-toolchain-support %} |
+[Rust toolchain](#rust-toolchain) | `rust-toolchain` | Not applicable | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} | {% octicon "check" aria-label="Supported" %} | Not applicable   | Not applicable   |
+| {% endif %} |
 [Swift](#swift)      | `swift`      | v5  | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} (git only) | {% octicon "x" aria-label="Not supported" %} |
 [Terraform](#terraform)      | `terraform`      | >= 0.13, <= 1.10.x  | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | Not applicable |
 uv        | `uv`            | v0               | {% octicon "check" aria-label="Supported" %} | {% octicon "x" aria-label="Not supported" %} | {% octicon "check" aria-label="Supported" %} | {% octicon "check" aria-label="Supported" %} | Not applicable |
@@ -153,6 +156,19 @@ The PEP 621 `project` section isn't currently supported for `poetry`.
 
 You can use {% data variables.product.prodname_dependabot %} to keep Dart dependencies up-to-date if you use private hosted pub repositories. For information about allowing {% data variables.product.prodname_dependabot %} to access private {% data variables.product.prodname_dotcom %} dependencies, see [Allowing {% data variables.product.prodname_dependabot %} to access private dependencies](/organizations/keeping-your-organization-secure/managing-security-settings-for-your-organization/managing-security-and-analysis-settings-for-your-organization#allowing-dependabot-to-access-private{% ifversion ghec or ghes %}-or-internal{% endif %}-dependencies).
 
+{% ifversion dependabot-rust-toolchain-support %}
+
+#### Rust toolchain
+
+{% data variables.product.prodname_dependabot %} supports automatic updates for Rust toolchain versions defined in `rust-toolchain.toml` and `rust-toolchain` files.
+
+Supported update patterns {% data variables.product.prodname_dependabot %} can update:
+
+* Versioned toolchains such as `channel = "1.xx.yy"` and `channel = "1.xx"`.
+* Dated toolchains such as `channel = "nightly-YYYY-MM-DD"` and `channel = "beta-YYYY-MM-DD"`.
+
+{% endif %}
+
 #### Swift
 
 Private registry support applies to git registries only. Swift registries are not supported. Non-declarative manifests are not supported. For more information on non-declarative manifests, see [Editing Non-Declarative Manifests](https://github.com/apple/swift-evolution/blob/7003da1439ad60896ec14657dfce829f04b0632c/proposals/0301-package-editing-commands.md#editing-non-declarative-manifests) in the Swift Evolution documentation.