fix: add missing INSTALLATION_ID to example env files

INSTALLATION_ID is a required environment variable but was missing from
the example env files. This caused deployment failures with the error:
'missing required environment variables: INSTALLATION_ID'

Added INSTALLATION_ID back to:
- configs/env.yaml.example
- configs/env.yaml.production

Author: cbullinger

examples-copier/configs/env.yaml.example

@@ -5,6 +5,7 @@ env_variables:
 
   # GitHub App Configuration
   GITHUB_APP_ID: "YOUR_GITHUB_APP_ID"              # Your GitHub App ID (required)
+  INSTALLATION_ID: "YOUR_INSTALLATION_ID"          # GitHub App Installation ID (required)
 
   # Config Repository (where copier-config.yaml is stored)
   CONFIG_REPO_OWNER: "your-org"                    # Config repository owner (required)

examples-copier/configs/env.yaml.production

@@ -2,6 +2,7 @@
 # GitHub Configuration (Non-sensitive)
 # =============================================================================
 GITHUB_APP_ID: "1166559"
+INSTALLATION_ID: "YOUR_INSTALLATION_ID"  # Replace with your GitHub App Installation ID
 
 # Config Repository (where copier-config.yaml is stored)
 CONFIG_REPO_OWNER: "mongodb"