doc: add heading IDs to Code of Conduct

Fixes #13514

Change-Id: I3903d3926ed4f5d54cfb77209d93c950b832b933
Reviewed-on: https://go-review.googlesource.com/17511
Reviewed-by: Francesc Campoy Flores <campoy@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

doc/conduct.html

@@ -13,9 +13,9 @@
 }
 </style>
 
-<h2>About the Code of Conduct</h2>
+<h2 id="about">About the Code of Conduct</h2>
 
-<h3>Why have a Code of Conduct?</h3>
+<h3 id="why">Why have a Code of Conduct?</h3>
 
 <p>
 Online communities include people from many different backgrounds.
@@ -49,7 +49,7 @@ <h3>Why have a Code of Conduct?</h3>
 they disagree.
 </p>
 
-<h3>Where does the Code of Conduct apply?</h3>
+<h3 id="spaces">Where does the Code of Conduct apply?</h3>
 
 <p>
 If you participate in or contribute to the Go ecosystem in any way,
@@ -76,7 +76,7 @@ <h3>Where does the Code of Conduct apply?</h3>
 moderators and/or working group (see below).
 </p>
 
-<h2>Gopher values</h2>
+<h2 id="values">Gopher values</h2>
 
 <p>
 These are the values to which people in the Go community (“Gophers”) should aspire.
@@ -130,7 +130,7 @@ <h2>Gopher values</h2>
 It is the responsibility of <i>all parties</i> to de-escalate conflict when it arises.
 </p>
 
-<h2>Unwelcome behavior</h2>
+<h2 id="unwelcome_behavior">Unwelcome behavior</h2>
 
 <p>
 These actions are explicitly forbidden in Go spaces:
@@ -145,7 +145,7 @@ <h2>Unwelcome behavior</h2>
 <li>Incitement to any of these.
 </ul>
 
-<h2>Moderation</h2>
+<h2 id="moderation">Moderation</h2>
 
 <p>
 The Go spaces are not free speech venues; they are for discussion about Go.
@@ -174,7 +174,7 @@ <h2>Moderation</h2>
 below.
 </p>
 
-<h2>Reporting issues</h2>
+<h2 id="reporting">Reporting issues</h2>
 
 <p>
 The Code of Conduct Working Group is a group of people that represent the Go
@@ -256,7 +256,7 @@ <h2>Reporting issues</h2>
 <a href="https://golang.org/s/proposal-process">change proposal process</a>.
 </p>
 
-<h2>Summary</h2>
+<h2 id="summary">Summary</h2>
 
 <ul>
 <li>Treat everyone with respect and kindness.
@@ -265,7 +265,7 @@ <h2>Summary</h2>
 <li>If you encounter an issue, please mail <a href="mailto:conduct@golang.org">conduct@golang.org</a>.
 </ul>
 
-<h3>Acknowledgements</h3>
+<h3 id="acknowledgements">Acknowledgements</h3>
 
 <p>
 Parts of this document were derived from the Code of Conduct documents of the