Add tuning tips

_locales/en/messages.json

@@ -812,6 +812,9 @@
     "receiverHelp": {
         "message": "Please read receiver chapter of the documentation.  Configure serial port (if required), receiver mode (serial/ppm/pwm), provider (for serial receivers), bind receiver, set channel map, configure channel endpoints/range on TX so that all channels go from ~1000 to ~2000.  Set midpoint (default 1500), trim channels to 1500, configure stick deadband, verify behaviour when TX is off or out of range.<br /><span style=\"color: red\">IMPORTANT:</span> Before flying read failsafe chapter of documentation and configure failsafe."
     },
+    "tuningHelp": {
+        "message": "Tuning tips<br><b>Derivative from Error</b> provides more direct stick response and is mostly prefered for Racing.<br><b>Derivative from Measurement</b> provides smoother stick response what is more usefull for freestyling<br><br /><span style=\"color: red\">IMPORTANT:</span> It is important to verify motor temperatures during first flights. The higher the filter value gets the better it may fly, but you do to get more noise into the motors. <br>Default value of 100hz is optimal, but for noiser setups you can try lowering Dterm filter to 50hz and possibly also the gyro filter."
+    },
     "receiverThrottleMid": {
         "message": "Throttle MID"
     },

tabs/pid_tuning.html

@@ -4,6 +4,11 @@
         <div class="cf_doc_version_bt">
             <a id="button-documentation" href="https://github.com/betaflight/betaflight/releases" target="_blank"></a>
         </div>
+        <div class="note">
+        <div class="note_spacer">
+            <p i18n="tuningHelp"></p>
+        </div>
+        </div>
         <div class="cf_column twothird">
             <div class="controller single-field">
                 <div class="head" i18n="pidTuningControllerHead"></div>