Remove fixed width from knowledge graph image in README

Let the image scale naturally to the viewport, consistent with
the SVG diagram approach.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Grivn

README.md

@@ -17,7 +17,7 @@ LLM agents forget everything between sessions. Context compaction drops critical
 Mnemon gives your agent persistent, cross-session memory — with a single binary and one setup command.
 
 <p align="center">
-  <img src="docs/diagrams/10-knowledge-graph.png" width="720" alt="Knowledge Graph — 87 insights connected by temporal, entity, semantic, and causal edges" />
+  <img src="docs/diagrams/10-knowledge-graph.png" alt="Knowledge Graph — 87 insights connected by temporal, entity, semantic, and causal edges" />
   <br />
   <sub>A real knowledge graph built by Mnemon — 87 insights, 2150 edges across four graph types.</sub>
 </p>