update to alpine 3.12

Dockerfile

@@ -1,12 +1,12 @@
-# simple netcat (BSD) persistent echo server running on port 5555
+# simple netcat (BSD) persistent "listen" server running on port 5555
 # running on Alpine Linux
 
-FROM alpine:3.11
+FROM alpine:3.12
 
 # standardized labels
 LABEL maintainer="Asif Bacchus <asif@bacchus.cloud>"
 LABEL org.label-schema.cmd="docker run --rm docker.asifbacchus.app/ab-netcat help"
-LABEL org.label-schema.description="Persistent netcat (BSD) echo server on Alpine Linux"
+LABEL org.label-schema.description="Persistent netcat (BSD) listen server on Alpine Linux"
 LABEL org.label-schema.name="ab-netcat"
 LABEL org.label-schema.schema-version="1.0"
 LABEL org.label-schema.url="https://git.asifbacchus.app/ab-docker/ab-netcat"

README.md

@@ -1,3 +1,15 @@
 # ab-netcat
 
-Simple netcat echo server on customizable port
+Simple BSD-style netcat (NC) persistent "listen" server running on Alpine Linux. Run `docker run --rm docker.asifbacchus.app/ab-netcat help` for a quick-reference usage overview.
+
+## Container usage
+
+General usage:
+
+`docker run [-d|-it] --init --rm -p [<ipaddr>:]<host port>:5555 [--name ab-netcat] [-e TZ=timezone] docker.asifbacchus.app/ab-netcat [/bin/sh]`
+
+Please consult the repo [wiki](https://git.asifbacchus.app/ab-docker/ab-netcat/wiki) for detailed usage instructions and notes.
+
+## Questions, Suggestions or Comments
+
+Please create an issue if anything needs to be fixed or you have suggestions for enhancements.  Otherwise, I hope it's useful to you!