add a Known Problems sections

Author: Shaoranlaos

README.md

@@ -99,4 +99,11 @@ Example:
 ## Getting Access Key and Secret Key
 
 The Credentials can be requested on the offical Ecoflow IoT Website: [Ecoflow OpenIoT](https://developer-eu.ecoflow.com).
-It can take up to a week for the account to be enabled.
+It can take up to a week for the account to be enabled.
+
+
+## Known "Problems"
+
+1. The API returns the last known values for a device that is offline. Please use the device list function and check the online status of a device bevor using the values (see the example flow "ListDevicesAndQuerThem"). 
+2. The online status in the device list can take up to 15 minutes (in my observations) to reflect when a device is offline.
+3. The PowerOcean seems to have a bug where it only reports values in the API if one of the offical Apps for it are open. See [#9](https://github.com/Shaoranlaos/node-red-contrib-ecoflow-http-api/issues/9) for the cuurent status on this.

ecoflow-api-node.html

@@ -92,7 +92,8 @@ <h3>Inputs</h3>
         <dt>function
             <span class="property-type">string</span>
         </dt>
-        <dd>The function to execute (for niche applications only, the function should be set on the node for better visibility).<br/>
+        <dd>The function to execute (for niche applications only, 
+            the function should be set on the node for better visibility).<br/>
             Can be one of
             <ul>
                 <li>queryQuotaAll</li>
@@ -111,7 +112,10 @@ <h3>Outputs</h3>
                 <span class="property-type">json</span></dt>
             <dd>the output of the command, see the 
                 <a href="https://developer-eu.ecoflow.com/us/document/generalInfo">documentation</a>
-                for structure and content</dd>
+                for structure and content<br/>
+                <b>Attention</b>: please see the "Known Problems" section in the <a href="https://flows.nodered.org/node/@shaoranlaos/node-red-contrib-ecoflow-http-api">Readme</a>
+                of the node for some "quirks" in the returned values.
+            </dd>
         </dl>
     </ol>