docs: Fix broken link

Author: andypugh

docs/html/gcode.html

@@ -68,7 +68,7 @@
 
     <tr><th>Canned cycles</th><td colspan="2">(X Y Z or U V W apply to canned cycles, depending on active plane)</td></tr>
     <tr><td><a href="gcode/g-code.html#gcode:g70">G70</a></td><td>Q (X) (Z) (D) (E) (P)</td><td>Lathe finishing cycle</td></tr>
-    <tr><td><a href="gcode/g-code.html#gcode:g71">G71 G72</a></td><td>Q (X) (Z) (D) (E) (P)</td><td>Lathe roughing cycle</td></tr>
+    <tr><td><a href="gcode/g-code.html#gcode:g71-g72">G71 G72</a></td><td>Q (X) (Z) (D) (E) (P)</td><td>Lathe roughing cycle</td></tr>
     <tr><td><a href="gcode/g-code.html#gcode:g73">G73</a></td><td>R L Q</td><td>Drilling Cycle, Chip Breaking</td></tr>
     <tr><td><a href="gcode/g-code.html#gcode:g74">G74</a></td><td>R L (P) ($)</td><td>Left-hand Tapping Cycle, Dwell</td></tr>
     <tr><td><a href="gcode/g-code.html#gcode:g76">G76</a></td><td>P Z I J R K Q H L E ($)</td><td>Threading Cycle</td></tr>