Merge pull request #2648 from buildkite/add-allowed-repositories-description-to-docs

Add 'allowed repositories' description to docs

Author: gilesgas

data/content/agent_attributes.yaml

@@ -4,19 +4,25 @@ attributes:
   default_value: None
   required: true
   desc: |
-      The agent registration token from your organization’s _Agents_ page, used only to register new agents. To get your token, log in to Buildkite, navigate to _Agents_, then select _Reveal Agent Token_.
-- name: bootstrap-script
-  env_var: BUILDKITE_BOOTSTRAP_SCRIPT_PATH
-  default_value: "buildkite-agent bootstrap"
-  required: false
-  desc: |
-      Command to invoke the bootstrap process.
+      The agent registration token from your organization's _Agents_ page, used only to register new agents. To get your token, log in to Buildkite, navigate to _Agents_, then select _Reveal Agent Token_.
 - name: build-path
   env_var: BUILDKITE_BUILD_PATH
   default_value: "(depends on platform)"
   required: true
   desc: |
       Path to where the builds will run from.
+- name: allowed-repositories
+  env_var: BUILDKITE_ALLOWED_REPOSITORIES
+  default_value: ""
+  required: false
+  desc: |
+      A comma-separated list of regular expressions representing repositories the agent is allowed to clone (for example, `^git@github.com:buildkite/.\*` or `^https://github.com/buildkite/.*`)
+- name: bootstrap-script
+  env_var: BUILDKITE_BOOTSTRAP_SCRIPT_PATH
+  default_value: "buildkite-agent bootstrap"
+  required: false
+  desc: |
+      Command to invoke the bootstrap process.
 - name: cancel-grace-period
   env_var: BUILDKITE_CANCEL_GRACE_PERIOD
   default_value: "10"