doc: fix typo in Programming FAQ

R=rsc, r2
CC=golang-dev
https://golang.org/cl/2186041

doc/go_programming_faq.html

@@ -3,7 +3,7 @@
 <h2 id="Pointers">Pointers and Allocation</h2>
 
 <h3 id="pass_by_value">
-When are function paramters passed by value?</h3>
+When are function parameters passed by value?</h3>
 
 <p>
 Everything in Go is passed by value.  A function always gets a copy of the