2014-12-24: link to GNU Guile

link to GNU Guile

diff --git a/docs/srfi-from-template.html b/docs/srfi-from-template.html
--- a/docs/srfi-from-template.html
+++ b/docs/srfi-from-template.html
@@ -687,7 +687,7 @@ You can still use underscores anywhere b
 
 <H1>Implementation</H1>
 
-<p>The reference implementation realizes a specialized parser for Scheme. It uses GNU Guile and can also be used at the REPL.</p>
+<p>The reference implementation realizes a specialized parser for Scheme. It uses <a href="https://gnu.org/s/guile" title="GNU Guile: The GNU extension language">GNU Guile</a> and can also be used at the REPL.</p>
 
 <p>The wisp code also contains a general wisp-preprocessor which can be used for any lisp-like language and can used as an external program which gets called on reading. It does not actually have to understand the code itself.</p>