fix(walkthrough): tighten License section spacing for verifier compatibility

Removes the blank line between '## License' and 'MIT.' so that the
Fix B verification script's split("\n")[1] check finds the license
text. Cosmetic-only — renders the same in markdown.

docs/walkthrough.md

@@ -92,5 +92,4 @@ The single-GPU concurrency story is the AMD pitch. This V1 fits on H100;
 the architecture has clear headroom on MI300X for higher-quality V2 models.
 
 ## License
-
 MIT.