add readme diff link

README.md

@@ -3,6 +3,7 @@
 The internet-draft is hosted at [draft-ietf-acme-dtnnodeid](https://datatracker.ietf.org/doc/draft-ietf-acme-dtnnodeid/).
 
 A local build of the current main branch is available [draft-ietf-acme-dtnnodeid.html](https://briansipos.github.io/acme-dtnnodeid/draft-ietf-acme-dtnnodeid.html).
+A difference from the datatracker draft and this local version can be [viewed side-by-side](https://author-tools.ietf.org/diff?doc_1=draft-ietf-acme-dtnnodeid&url_2=https://briansipos.github.io/acme-dtnnodeid/draft-ietf-acme-dtnnodeid.txt&raw=1).
 
 # Demo Convergence Layer Agent