Added various vars to env sample

Added several vars that are already implemented to the .env.production.sample file.
-Max bio character limit 
-Number of profile fields allowed
-Max display name character limit

.env.production.sample

@@ -160,6 +160,15 @@ STREAMING_CLUSTER_NUM=1
 # Maximum number of pinned posts
 # MAX_PINNED_TOOTS=5
 
+# Maximum allowed bio characters
+# MAX_BIO_CHARS=500
+
+# Maximim number of profile fields allowed
+# MAX_PROFILE_FIELDS=4
+
+# Maximum allowed display name characters
+# MAX_DISPLAY_NAME_CHARS=30
+
 # Maximum image and video upload sizes
 # Units are in bytes
 # 1048576 bytes equals 1 megabyte