README: gcc and make are mandatory requirements

README.md

@@ -17,9 +17,9 @@ This Chef Handler is heavily based on [Joshua Timberman](https://github.com/jtim
 
 * Amazon AWS: uses Amazon SNS service.
 * Uses the `aws-sdk` library.
-  * `aws-sdk` requires `nokogiri`, which also requires one of the following two:
-    * `libxml2-dev` installed.
-    * `gcc` and `make` installed (this will install libxml2 internally).
+  * `aws-sdk` requires `nokogiri`, which also has the following requires:
+    * `libxml2-dev` and `libxslt-dev` installed (optional).
+    * `gcc` and `make` installed (this will compile and install libxml2 and libxslt internally if not found).
 * For `Ruby 1.8`, you need to install old versions of the following dependencies:
   * `mime-types < 2.0`.
   * `nokogiri < 1.6`.