Convert README to README.md and expand like in other projects

Let's align with structure and content of README.md in other osmo-*
projects.

Change-Id: Id9a78ccc0d10f0e3a9d832ac4c4988cfbb8ddb3c

Author: laf0rge

Makefile.am

@@ -24,7 +24,7 @@ pkgconfig_DATA = \
 BUILT_SOURCES = $(top_srcdir)/.version
 EXTRA_DIST = \
 	     .version \
-	     README \
+	     README.md \
 	     contrib/osmo-mgw.spec.in \
 	     debian \
 	     git-version-gen \

README

@@ -0,0 +1,102 @@
+osmo-mgw - Osmocom MGW (Media GateWay) Implementation
+=====================================================
+
+This repository contains a C-language implementation of an MGW (Media
+GateWay) for use [not only] within the 2G (GSM) and/or 3G (UMTS)
+Cellular Network built using Osmocom CNI (Cellular Network
+Infrastructure) software.
+
+The OsmoMGW program provides an MGCP interface towards an MGCP call agent
+(client) like OsmoMSC and OsmoBSC, and receives and sends RTP streams as
+configured via the MGCP control plane.
+
+This Media Gateway implementation is capable of
+
+* streaming RTP for 2G (3GPP AoIP and Abis-over-IP)
+* streaming RTP for 3G (IuCS including the IuFP protocol)
+* TDM (E1/T1) based Abis interface with TRAU frames on 16k sub-slots
+* basic support for LCLS (Local Call, Local Switch) related features
+* various built-in translation capabilities
+  * between Abis TRAU frames and RTP formats
+  * between 2G AMR/RTP and 3G AMR/IuFP/RTP
+  * between bandwidth-efficient and octet-aligned AMR
+  * between different standards for encapsulating GSM HR codec frames in RTP
+
+osmo-mgw is typically co-located with
+
+ * osmo-bsc (GSM BSC)
+ * osmo-msc (GSM/UMTS MSC)
+ * osmo-hnbgw (UMTS HNBGW); osmo-mgw implements RTP relay between Iuh
+   and IuCS interfaces
+
+The libosmo-mgcp-client library exposes utilities used by e.g. OsmoMSC
+(found in osmo-msc.git) to instruct OsmoMGW via its MGCP service.
+
+Homepage
+--------
+
+You can find the OsmoMGW issue tracker and wiki online at
+<https://osmocom.org/projects/osmo-mgw> and <https://osmocom.org/projects/osmo-mgw/wiki>.
+
+
+GIT Repository
+--------------
+
+You can clone from the official osmo-mgw.git repository using
+
+        git clone https://gitea.osmocom.org/cellular-infrastructure/osmo-mgw
+
+There is a web interface at <https://gitea.osmocom.org/cellular-infrastructure/osmo-mgw>
+
+
+Documentation
+-------------
+
+User Manuals and VTY reference manuals are [optionally] built in PDF form
+as part of the build process.
+
+Pre-rendered PDF version of the current "master" can be found at
+[User Manual](https://ftp.osmocom.org/docs/latest/osmomgw-usermanual.pdf)
+as well as the [VTY Reference Manual](https://ftp.osmocom.org/docs/latest/osmomgw-vty-reference.pdf)
+
+
+Mailing List
+------------
+
+Discussions related to osmo-mgw are happening on the
+[email protected] mailing list, please see
+<https://lists.osmocom.org/mailman/listinfo/openbsc> for subscription
+options and the list archive.
+
+Please observe the [Osmocom Mailing List
+Rules](https://osmocom.org/projects/cellular-infrastructure/wiki/Mailing_List_Rules)
+when posting.
+
+
+Contributing
+------------
+
+Our coding standards are described at
+<https://osmocom.org/projects/cellular-infrastructure/wiki/Coding_standards>
+
+We use a gerrit based patch submission/review process for managing
+contributions.  Please see
+<https://osmocom.org/projects/cellular-infrastructure/wiki/Gerrit> for
+more details
+
+The current patch queue for osmo-mgw can be seen at
+<https://gerrit.osmocom.org/#/q/project:osmo-mgw+status:open>
+
+
+History
+-------
+
+OsmoMGW originated from the OpenBSC project, which started as a minimalistic
+all-in-one implementation of the GSM Network. In 2017, OpenBSC had reached
+maturity and diversity (including M3UA SIGTRAN and 3G support in the form of
+IuCS and IuPS interfaces) that naturally lead to a separation of the all-in-one
+approach to fully independent separate programs as in typical GSM networks.
+
+OsmoMGW was one of the parts split off from the old openbsc.git. It originated
+as a solution to merely navigate RTP streams through a NAT, but has since
+matured.

README.md

@@ -99,7 +99,7 @@ make %{?_smp_mflags} check || (find . -name testsuite.log -exec cat {} +)
 
 %files
 %license COPYING
-%doc AUTHORS README
+%doc AUTHORS README.md
 %dir %{_docdir}/%{name}/examples
 %dir %{_docdir}/%{name}/examples/osmo-mgw
 %{_docdir}/%{name}/examples/osmo-mgw/osmo-mgw.cfg