chore: replace nomad references with trek in update instructions and CI

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

.github/workflows/docker.yml

@@ -145,8 +145,6 @@ jobs:
           docker buildx imagetools create \
             -t mauriceboe/trek:latest \
             -t mauriceboe/trek:$VERSION \
-            -t mauriceboe/nomad:latest \
-            -t mauriceboe/nomad:$VERSION \
             "${digests[@]}"
 
       - name: Inspect manifest