fix(aidoc_classes): Improve commit message generation by handling empty diffs and updating changelog instructions

ts/aidocs_classes/commit.ts

@@ -29,8 +29,9 @@ export class Commit {
     contextString = `
 ${contextString}
 
-Here is the diff:
-${diffString}
+Below is the diff of the uncommitted changes. If nothing is changed, there are no changes:
+
+${diffString || 'No changes.'}
     `
 
     let result = await this.aiDocsRef.openaiInstance.chat({
@@ -83,6 +84,7 @@ You are given
 Only return the changelog file, so it can be written directly to changelog.md
 
 For the latest version, that is not yet part of the commit messages, use {{nextVersion}} and {{nextVersionMessage}} placeholders.
+Only output newer versions and their changes compared to ones already mentioned. We take of appending your output later.
       `,
       userMessage: `
 The previous changelog file is: