add a generated comment to spin-dependencies.wit (#3515)

Signed-off-by: Karthik Ganeshram <kganeshr@akamai.com>

Author: karthik2804

crates/dependency-wit/src/lib.rs

@@ -7,6 +7,8 @@ use spin_serde::DependencyName;
 use wit_component::DecodedWasm;
 use wit_parser::Span;
 
+const GENERATED_COMMENT: &str = "// This file is automatically generated by Spin\n// It is not intended for manual editing.\n\n";
+
 pub async fn extract_wits_into(
     source: impl ExactSizeIterator<Item = (&DependencyName, &ComponentDependency)>,
     app_root: impl AsRef<Path>,
@@ -19,7 +21,11 @@ pub async fn extract_wits_into(
         return Ok(());
     }
 
-    let wit_text = extract_wits(source, app_root).await?;
+    let wit_text = format!(
+        "{}{}",
+        GENERATED_COMMENT,
+        extract_wits(source, app_root).await?
+    );
 
     tokio::fs::create_dir_all(
         dest_file