Ranch is supported on R15B01+

Add a script that runs the test suite on all Erlang versions
starting from R15B01.

R15B is not supported due to issues with sendfile.

all.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+KERL_INSTALL_PATH=~/erlang
+KERL_RELEASES="r15b01 r15b02 r15b03 r16b r16b01 r16b02"
+
+make build-tests
+
+for rel in $KERL_RELEASES
+do
+	echo
+	echo "    TESTING $rel"
+	echo
+	. $KERL_INSTALL_PATH/$rel/activate
+	cp ~/.kerl/builds/$rel/otp_src_*/lib/ssl/test/erl_make_certs.erl \
+		deps/ct_helper/src/
+	make tests
+done
+
+xdg-open logs/all_runs.html

guide/introduction.md

@@ -15,3 +15,18 @@ Prerequisites
 
 It is assumed the developer already knows Erlang and has some experience
 with socket programming and TCP protocols.
+
+Supported platforms
+-------------------
+
+Ranch is tested and supported on Linux.
+
+Ranch has been reported to work on other platforms, but we make no
+guarantee that the experience will be safe and smooth. You are advised
+to perform the necessary testing and security audits prior to deploying
+on other platforms.
+
+Ranch is developed for Erlang R15B01 and later versions.
+
+Ranch may be compiled on earlier Erlang versions with small source code
+modifications but there is no guarantee that it will work as expected.