doc: Update website Doxygen link

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>

Author: freddy77

doc/htdoc/docs.html

@@ -49,7 +49,12 @@
 
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-The FreeTDS <a href="reference/">Reference Manual</a> is our start at documenting the APIs.  In general, the definitive API documentation is available online from the vendors.  It will be a big job for us to replace that, and at the rate we're going, we never will.  Our first goal is to document our implementation: which functions work, and how well.  We haven't reached even that goal yet.  The reference manual is generated with <a href="http://www.stack.nl/~dimitri/doxygen/">Doxygen</a>.
+The FreeTDS <a href="reference/">Reference Manual</a> is our start at documenting the APIs.
+In general, the definitive API documentation is available online from the vendors.
+It will be a big job for us to replace that, and at the rate we're going, we never will.
+Our first goal is to document our implementation: which functions work, and how well.
+We haven't reached even that goal yet.
+The reference manual is generated with <a href="https://www.doxygen.nl">Doxygen</a>.
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