[survey-web/oscp] Add note for future self

[Bartłomiej Piotrowski <bpiotrowski src gnome org>]

commit 9f6de620c01b55db58a0f86de0b58125f91e7211
Author: Bartłomiej Piotrowski <bpiotrowski gnome org>
Date:   Mon Mar 9 07:45:44 2020 +0100

    Add note for future self

 docker/Dockerfile | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 08197a6..4083198 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -25,6 +25,9 @@ RUN chmod -R a+rwx /app/limesurvey/upload
 RUN chmod -R a+rwx /app/limesurvey/themes
 RUN chmod -R a+rwx /app/limesurvey/application/config
 
+# Regression in recent LimeSurvey releases causes it to attempt to decrypt
+# unencrypted answers on submission, resulting in 500 error page instead of
+# successful submission screen.
 RUN sed -i '112d' /app/limesurvey/application/core/LSSodium.php
 
 COPY run.sh /tmp/entrypoint.sh