remove and ignor plan.md

Signed-off-by: Angelo De Caro <adc@zurich.ibm.com>

Author: adecaro

.gitignore

@@ -14,6 +14,7 @@ cmd/token_validation_service/out/
 /site/
 coverage.out
 /.codex/
+plan.md
 
 # The EVM integration suites generate a node binary tree and a network under out/ and testdata/.
 # Both hold real Go files, so a stray "git add -A" commits them and a linter then reports on them.