docs(knowledge-base): add guide for wmts connection in qgis

docs/KnowledgeBase/Desktop applications/_category_.json

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+{
+    "position": 3
+}

docs/KnowledgeBase/Desktop applications/qgis-wmts.md

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+---
+id: qgis-wmts
+slug: qgis-wmts
+title: Add WMTS connection in QGIS
+sidebar_position: 2
+tags:
+  - qgis
+  - wmts
+  - connection
+---
+
+## Prerequisites
+
+### MapColonies token
+
+In order to create a connection to our `WMTS` service you will need a `token`, contact us to receive one.
+
+[Read more about `tokens`](/docs/MapColonies/auth.md).
+
+### QGIS application
+
+Install the `QGIS` application (version >3.26).
+
+## Create a new connection in QGIS
+
+Open your `QGIS` application. In the browser windows (on the left), right click on `WMS/WMTS` and select `New Connection...`.
+
+<figure>
+    <img src={require("/img/qgis/qgis-wmts-add-connection.png").default} style={{"display":"block","marginLeft":"auto","marginRight":"auto","height":"350px"}}/>
+</figure>
+
+A connection creation form will open, fill the following:
+1. `Name` - connection name
+2. `URL` - `WMTS Cpabilities` URL provided by us
+
+Now click on `Advanced` under `HTTP Headers` and add a new header with the `Key` "x-api-key" and the value will be the `token` provided by us.
+
+At the end of the process the form should look similar to this:
+
+<figure>
+    <img src={require("/img/qgis/qgis-wmts-new-connection.png").default} style={{"display":"block","marginLeft":"auto","marginRight":"auto","height":"500px"}}/>
+</figure>
+
+Click `OK` to create the connection. Now we can see it under `WMS/WMTS`:
+
+<figure>
+    <img src={require("/img/qgis/qgis-wmts-connection.png").default} style={{"display":"block","marginLeft":"auto","marginRight":"auto"}}/>
+</figure>
+
+Drag any layer to the `Layers` panel in order to view it.
+
+And that's it, you are ready to start working with with our service and your data!