Update retraction instruction

Thanks Andrew.

calibration.html

@@ -768,7 +768,7 @@ <h2>Interpreting Results:</h2>
             <h5>I can't translate my test results to my own slicer! Other factors beyond the scope of this test - <span style="color:red;">Important!</span></h5>
             <p>After you have found a combination of parameters which works well on your machine, the idea is to then translate them  to your own slicing profile. If you can't replicate the results, please work through the following:</p>
             <ul>
-                <li>Auto cooling (PrusaSlicer) / Speed Overrides (Simplify3D) / Minimum layer time (Cura): Most slicers have a setting to detect if a layer will complete in less than a certain time threshold. In this case, all movement for that layer is slowed, including those related to retraction, to increase the layer time to meet the target. The gcode generated by the this page has this setting OFF. If your results vary, trying turning this setting off in your own slicer too.</li>
+                <li>Slow down is layer time is below (PrusaSlicer) / Speed Overrides (Simplify3D) / Minimum layer time (Cura): Most slicers have a setting to detect if a layer will complete in less than a certain time threshold. In this case, all movement for that layer is slowed, including those related to retraction, to increase the layer time to meet the target. The gcode generated by the this page has this setting OFF. If your results vary, trying turning this setting off in your own slicer too.</li>
                 <li>Z hop speed: If you are using Z hop, the vertical feedrate for the Z movements is set to 20 mm/sec for these tests. Matching this in your slicer is advised if these tests look better than your own slicer results.</li>
                 <li>Retraction acceleration: This will affect whether the retraction speed can actually be reached. The gcode generator below does not include any changes to what is set on your printer. You can change this with <a href="https://marlinfw.org/docs/gcode/M204.html" target="_blank">M204</a> and the <b>R</b> argument.</li>
                 <li>Slicer settings such as coast and wipe: Coast stops extrusion slightly early to assist retraction. It effectively lets the hot end 'run dry' at the end of the printing movement to reduce ooze. This varies from slicer to slicer and isn't always necessary to tune.