docs: added some inline comments

src/app.ts

@@ -60,6 +60,7 @@ async function configureApp() {
 
     // Only accept json as content type
     if (contentType === '' || contentType.match(/^application\/json$/) === null) {
+      // return an error in the response
       const err = new SCUnsupportedMediaTypeErrorResponse(isTestEnvironment);
       res.status(err.statusCode);
       res.json(err);
@@ -67,17 +68,21 @@ async function configureApp() {
     }
 
     const bodyBuffer: any[] = [];
+    // we don't know the full size, the only way we can get is by adding up all individual chunk sizes
     let bodySize = 0;
     const chunkGatherer = (chunk: Buffer) => {
       bodySize += chunk.byteLength;
+      // when adding each chunk size to the total size, check how large it now is.
       if (bodySize > 512 * 1024) {
         req.off('data', chunkGatherer);
         req.off('end', endCallback);
+        // return an error in the response
         const err = new SCRequestBodyTooLargeErrorResponse(isTestEnvironment);
         res.status(err.statusCode);
         res.json(err);
         return;
       }
+      // push the chunk in the buffer
       bodyBuffer.push(chunk);
     };