Add YouTube tutorial

docs/how_to_get_youtube_api_key.md

@@ -0,0 +1,23 @@
+# How to get YouTube API Key
+
+1. Navigate to https://console.developers.google.com
+2. Click `Select a project`.
+![Select project](img/youtube_select_project.png)
+3. Click `New project`.
+![New project](img/youtube_new_project.png)
+4. Give it a name and click `Create` button.
+![Dashboard](img/youtube_dashboard.png)
+5. Click `Library`, find and click on `YouTube Data API v3` box.
+![YouTube Data API](img/youtube_data_api_v3.png)
+6. Click `Enable`.
+![YouTube Enable](img/youtube_data_api_enable.png)
+5. Click `Credentials`.
+6. Click `Create credentials`.
+7. Select `API key`.
+![Create API key](img/youtube_create_api_key.png)
+8. Copy token to your CLI's configuration file.
+![Copy token](img/youtube_copy_token.png)
+```toml
+[tokens]
+youtube = "AIzaSyD4w2s-k79YNR98ABC"
+```