Add roles descriptions to roles.sh (#1583)

In order to clarify what the roles are.

Author: cedricvidal

scripts/roles.sh

@@ -9,11 +9,11 @@ done <<< "$output"
 echo "Environment variables set."
 
 roles=(
-    "5e0bd9bd-7b93-4f28-af87-19fc36ad61bd"
-    "2a2b9908-6ea1-4ae2-8e65-a410df84e7d1"
-    "ba92f5b4-2d11-453d-a403-e96b0029c9fe"
-    "1407120a-92aa-4202-b7e9-c0e197c71c8f"
-    "8ebe5a00-799e-43f5-93ac-243d3dce84a7"
+    "5e0bd9bd-7b93-4f28-af87-19fc36ad61bd" # Cognitive Services OpenAI User
+    "2a2b9908-6ea1-4ae2-8e65-a410df84e7d1" # Storage Blob Data Reader
+    "ba92f5b4-2d11-453d-a403-e96b0029c9fe" # Storage Blob Data Contributor
+    "1407120a-92aa-4202-b7e9-c0e197c71c8f" # Search Index Data Reader
+    "8ebe5a00-799e-43f5-93ac-243d3dce84a7" # Search Index Data Contributor
 )
 
 if [ -z "$AZURE_RESOURCE_GROUP" ]; then