Update README to mention config.pl
diff --git a/README.rst b/README.rst
index 2abec3c..43253be 100644
--- a/README.rst
+++ b/README.rst
@@ -2,6 +2,15 @@
README for PolarSSL
===================
+Configuration
+=============
+
+PolarSSL should build out of the box on most systems. Some platform specific options are available in the fully-documented configuration file *include/polarssl/config.h*, which is also the place where features can be selected.
+This file can be edited manually, or in a more programmatic way using the Perl
+script *scripts/config.pl* (use *--help* for usage instructions).
+
+Compiler options can be set using standard variables such as *CC* and *CFLAGS* when using the Make and CMake build system (see below).
+
Compiling
=========