doc: Fixed type in documentation for FormatFloat.

R=r, r, rsc
CC=golang-dev
https://golang.org/cl/5656108

Author: mpvl

doc/go1.html

@@ -1705,7 +1705,7 @@ <h3 id="strconv">The strconv package</h3>
 <tr>
 <td colspan="2"><hr></td>
 </tr>
-<tr><td>Ftoa32(x, f, p)</td> <td>FormatFloat(x, float64(f), p, 32)</td></tr>
+<tr><td>Ftoa32(x, f, p)</td> <td>FormatFloat(float64(x), f, p, 32)</td></tr>
 <tr><td>Ftoa64(x, f, p)</td> <td>FormatFloat(x, f, p, 64)</td></tr>
 <tr><td>FtoaN(x, f, p, n)</td> <td>FormatFloat(x, f, p, n)</td></tr>
 <tr>

doc/go1.tmpl

@@ -1590,7 +1590,7 @@ for full details.
 <tr>
 <td colspan="2"><hr></td>
 </tr>
-<tr><td>Ftoa32(x, f, p)</td> <td>FormatFloat(x, float64(f), p, 32)</td></tr>
+<tr><td>Ftoa32(x, f, p)</td> <td>FormatFloat(float64(x), f, p, 32)</td></tr>
 <tr><td>Ftoa64(x, f, p)</td> <td>FormatFloat(x, f, p, 64)</td></tr>
 <tr><td>FtoaN(x, f, p, n)</td> <td>FormatFloat(x, f, p, n)</td></tr>
 <tr>