Fixed typo in MRR feedrate input

Author: mikecentola

src/webviews/apps/calc/calc.html

@@ -74,7 +74,7 @@ <h3>Metal Removal Rate</h3>
                         <vscode-divider role="separator"></vscode-divider>
                         <vscode-text-field id="mrr-ap" placeholder="Axial Depth of Cut" size="15">A<sub>p</sub> - Axial Depth of Cut</vscode-text-field>
                         <vscode-text-field id="mrr-ae" placeholder="Radial Depth of Cut" size="15">A<sub>e</sub> - Radial Depth of Cut</vscode-text-field>
-                        <vscode-text-field id="mrr-fr" placeholder="Feedrate" size="15">Feedrate</vscode-text-field>
+                        <vscode-text-field id="mrr-fr" placeholder="Enter Feedrate" size="15">Feedrate</vscode-text-field>
                         <label class="results">Metal Removal Rate</label><span id="mrr-results" class="results"></span>
                         <vscode-button id="mrr-calc-btn">Calculate</vscode-button>
                     </section>