Update README.md

Update mbedtls library version

Author: xqdoo00o

README.md

@@ -277,7 +277,7 @@ popd
 sudo ldconfig
 
 # Installation of MbedTLS
-export MBEDTLS_VER=2.5.1
+export MBEDTLS_VER=2.6.0
 wget https://tls.mbed.org/download/mbedtls-$MBEDTLS_VER-gpl.tgz
 tar xvf mbedtls-$MBEDTLS_VER-gpl.tgz
 pushd mbedtls-$MBEDTLS_VER