Gopher: document the feature in redis.conf.

Author: antirez

redis.conf

@@ -1183,6 +1183,61 @@ latency-monitor-threshold 0
 #  specify at least one of K or E, no events will be delivered.
 notify-keyspace-events ""
 
+############################### GOPHER SERVER #################################
+
+# Redis contains an implementation of the Gopher protocol, as specified in
+# the RFC 1436 (https://www.ietf.org/rfc/rfc1436.txt).
+#
+# The Gopher protocol was very popular in the late '90s. It is an alternative 
+# to the web, and the implementation both server and client side is so simple
+# that the Redis server has just 100 lines of code in order to implement this
+# support.
+#
+# What do you do with Gopher nowadays? Well Gopher never *really* died, and
+# lately there is a movement in order for the Gopher more hierarchical content
+# composed of just plain text documents to be resurrected. Some want a simpler
+# internet, others believe that the mainstream internet became too much
+# controlled, and it's cool to create an alternative space for people that
+# want a bit of fresh air.
+#
+# Anyway for the 10nth birthday of the Redis, we gave it the Gopher protocol
+# as a gift.
+#
+# --- HOW IT WORKS? ---
+#
+# The Redis Gopher support uses the inline protocol of Redis, and specifically
+# two kind of inline requests that were anyway illegal: an empty request
+# or any request that starts with "/" (there are no Redis commands starting
+# with such a slash). Normal RESP2/RESP3 requests are completely out of the
+# path of the Gopher protocol implementation and are served as usually as well.
+#
+# If you open a connection to Redis when Gopher is enabled and send it
+# a string like "/foo", if there is a key named "/foo" it is served via the
+# Gopher protocol.
+#
+# In order to create a real Gopher "hole" (the name of a Gopher site in Gopher
+# talking), you likely need a script like the following:
+#
+#   https://github.com/antirez/gopher2redis
+#
+# --- SECURITY WARNING ---
+#
+# If you plan to put Redis on the internet in a publicly accessible address
+# to server Gopher pages MAKE SURE TO SET A PASSWORD to the instance.
+# Once a password is set:
+#
+#   1. The Gopher server (when enabled, not by default) will kill serve
+#      content via Gopher.
+#   2. However other commands cannot be called before the client will
+#      authenticate.
+#
+# So use the 'requirepass' option to protect your instance.
+#
+# To enable Gopher support uncomment the following line and set
+# the option from no (the default) to yes.
+#
+# gopher-enabled no
+
 ############################### ADVANCED CONFIG ###############################
 
 # Hashes are encoded using a memory efficient data structure when they have a