doc/go1.17: fix a typo introduced in CL 335135

Change-Id: I62388bcb6d6f910ffa95d3db856ea29838573256
Reviewed-on: https://go-review.googlesource.com/c/go/+/340590
Trust: Bryan C. Mills <[email protected]>
Run-TryBot: Bryan C. Mills <[email protected]>
Reviewed-by: Rob Pike <[email protected]>

Author: Bryan C. Mills

doc/go1.17.html

@@ -150,7 +150,7 @@ <h4 id="graph-pruning">Pruned module graphs in <code>go 1.17</code> modules</h4>
   the pruned module graph, the <code>go.mod</code> file for each module needs to
   include more detail about the transitive dependencies relevant to that module.
   If a module specifies <code>go</code> <code>1.17</code> or higher in its
-  <code>go.mod</code> file, its <codeg>go.mod</code> file now contains an
+  <code>go.mod</code> file, its <code>go.mod</code> file now contains an
   explicit <a href="/ref/mod#go-mod-file-require"><code>require</code>
   directive</a> for every module that provides a transitively-imported package.
   (In previous versions, the <code>go.mod</code> file typically only included