build: require OpenSSL >= 1.1.1

Change-Id: I17a09ac60b867617af7a49fe19ab6e906dc14f61
diff --git a/docs/INSTALL.rst b/docs/INSTALL.rst
index d97236d..3fb4e59 100644
--- a/docs/INSTALL.rst
+++ b/docs/INSTALL.rst
@@ -36,7 +36,7 @@
 -  Python >= 3.6
 -  pkg-config
 -  Boost >= 1.65.1
--  OpenSSL >= 1.0.2
+-  OpenSSL >= 1.1.1
 -  SQLite 3.x
 
 To build ndn-cxx from source, one must first install a C++ compiler and all necessary