document RFC spec download behavior

.github/workflows/ci_compliance.yml

@@ -51,6 +51,12 @@ jobs:
         run: |
           # If this fails you need to run `cd compliance && ./compliance/initialize_duvet.sh`
           #
+          # FIXME: https://github.com/aws/s2n-tls/issues/4219
+          # We generate and commit the spec files to avoid re-downloading them each time in
+          # the CI (avoid flaky network calls). However, this currently doesn't work in
+          # s2n-tls since duvet assumes that the specs folder live in the project's base
+          # folder.
+          #
           # Use 'git status --porcelain' instead of 'git diff --exit-code' since git diff
           # only detects diffs but fails to detect new files. Ignore the s2n-quic dir
           # `(:!s2n-quic)` since we explicitly clone the repo as part of this job.