chore: clean up .env.example comment formatting + empty values

Author: iiio2

.env.example

@@ -1,5 +1,5 @@
-#secure password, can use openssl rand -hex 32
-NUXT_SESSION_PASSWORD=""
+# secure password, can use openssl rand -hex 32
+NUXT_SESSION_PASSWORD=
 
-#HMAC secret for image-proxy and OG image URL signing, can use openssl rand -hex 32
-NUXT_IMAGE_PROXY_SECRET=""
+# HMAC secret for image-proxy and OG image URL signing, can use openssl rand -hex 32
+NUXT_IMAGE_PROXY_SECRET=