Drop support for Erlang/OTP 18

Makefile

@@ -24,10 +24,10 @@ dep_ct_helper = git https://github.com/ninenines/ct_helper master
 dep_ci.erlang.mk = git https://github.com/ninenines/ci.erlang.mk master
 DEP_EARLY_PLUGINS = ci.erlang.mk
 
-AUTO_CI_OTP ?= OTP-18+
+AUTO_CI_OTP ?= OTP-19+
 AUTO_CI_HIPE ?= OTP-LATEST
 # AUTO_CI_ERLLVM ?= OTP-LATEST
-AUTO_CI_WINDOWS ?= OTP-18+
+AUTO_CI_WINDOWS ?= OTP-19+
 
 # Standard targets.
 

doc/src/guide/introduction.asciidoc

@@ -15,10 +15,7 @@ with socket programming and TCP protocols.
 
 Ranch is tested and supported on Linux, FreeBSD, OSX and Windows.
 
-Ranch is developed for Erlang/OTP 18+.
-
-There are known issues with the SSL application found in Erlang/OTP
-18.3.2 and 18.3.3. These versions are therefore not supported.
+Ranch is developed for Erlang/OTP 19+.
 
 Ranch may be compiled on earlier Erlang versions with small source code
 modifications but there is no guarantee that it will work as expected.