docs: add branchName and repoName as general template variables (#24)

Documents the new `{{{branchName}}}` and `{{{repoName}}}` template
variables introduced in GoodRxOSS/lifecycle#129.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: vigneshrajsb

src/pages/docs/features/template-variables.mdx

@@ -7,6 +7,7 @@ tags:
   - publicUrl
   - sha
   - branchName
+  - repoName
   - UUID
   - internalHostname
   - review
@@ -27,6 +28,8 @@ The following template variables are available for use within your configuration
 - **`{{{buildUUID}}}`** - The unique identifier for the Lifecycle environment, e.g., `lively-down-881123`.
 - **`{{{namespace}}}`** - Namespace for the deployments, e.g., `env-lively-down-881123`.
 - **`{{{pullRequestNumber}}}`** - The GitHub pull request number associated with the environment.
+- **`{{{branchName}}}`** - The branch name of the pull request that triggered the environment.
+- **`{{{repoName}}}`** - The full repository name (e.g., `org/repo`) associated with the environment.
 
 ### Service-Specific Variables