The go1.html file found in the net repository:

https://github.com/golang/net/blob/master/html/testdata/go1.html

...contains the following text implying that the HTML itself is licensed under "Creative Commons Attribution 3.0 License":

<div id="footer">
Build version go1.0.1.<br>
Except as <a href="http://code.google.com/policies.html#restrictions">noted</a>,
the content of this page is licensed under the
Creative Commons Attribution 3.0 License,
and code is licensed under a <a href="/LICENSE">BSD license</a>.<br>
<a href="/doc/tos.html">Terms of Service</a> | 
<a href="http://www.google.com/intl/en/privacy/privacy-policy.html">Privacy Policy</a>
</div>

However, it does not specify whether that is the US version (https://creativecommons.org/licenses/by/3.0/us/) or the unported version (https://creativecommons.org/licenses/by/3.0/). I'm assuming the US version. This is also slightly confusing as the LICENSE file found at the top of the net repository would lead many to believe that the HTML files fall under the standard 3-Clause BSD license that Go typically uses.

Regardless, the real issue appears to be that the policies.html page referenced in the footer text no longer exists, so it's unclear what license should apply to this content.