add comment why we compile openssl ourselves

docker/Dockerfile

@@ -1,5 +1,9 @@
 # https://github.com/openssl/openssl/releases/tag/openssl-3.5.2
 ARG OPENSSL_VERSION='3.5.2'
+
+# We compile openssl ourselves due to a memory leak in how crystal interacts
+# with openssl
+# Reference: https://github.com/iv-org/invidious/issues/1438#issuecomment-3087636228
 FROM crystallang/crystal:1.16.3-alpine AS dependabot-crystal
 
 FROM dependabot-crystal AS openssl-builder

docker/Dockerfile.arm64

@@ -1,5 +1,9 @@
 # https://github.com/openssl/openssl/releases/tag/openssl-3.5.2
 ARG OPENSSL_VERSION='3.5.2'
+
+# We compile openssl ourselves due to a memory leak in how crystal interacts
+# with openssl
+# Reference: https://github.com/iv-org/invidious/issues/1438#issuecomment-3087636228
 FROM alpine:3.21 AS dependabot-alpine
 
 FROM dependabot-alpine AS openssl-builder