Codelab/wiki: fix typo

Missing closing bracket renders the next code snippet unreadable.

R=adg, gri
CC=golang-dev
https://golang.org/cl/4119060

doc/codelab/wiki/index.html

@@ -710,7 +710,7 @@ Then we create an <code>init</code> function, which will be called before
 <code>ParseFile</code> that does not return an error code; instead, it panics
 if an error is encountered. A panic is appropriate here; if the templates can't
 be loaded the only sensible thing to do is exit the program.
-</p
+</p>
 
 <pre>
 func init() {

doc/codelab/wiki/wiki.html

@@ -574,7 +574,7 @@ Then we create an <code>init</code> function, which will be called before
 <code>ParseFile</code> that does not return an error code; instead, it panics
 if an error is encountered. A panic is appropriate here; if the templates can't
 be loaded the only sensible thing to do is exit the program.
-</p
+</p>
 
 <pre>
 !./srcextract.bin -src=final.go -name=init