add docs

Predefined-inquiries.md

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+Predefined inquiries come out of the box on the sqliteviz instance. In sqliteviz
+deployed on [Github Pages][1] there are no predefined inquiries, but you may
+see them if you use sqliteviz integrated into another app.
+
+These inquiries are shown in `Inqueries` list with a special label on the mouse
+over (fig. 1).
+
+<p align="center">
+   <img class="figure" src="./img/Screenshot_predefined.png?0.15.0"
+    width="700"/>
+</p>
+<p align="center">
+  <sub>
+    Fig. 1: Predefined inquiry
+  </sub>
+</p>
+
+As a user, you can't rename or delete a predefined inquiry. You can't save
+changes in a predefined inquiry, but you can save them as a new inquiry. The
+rest operations, copy and export, are available.
+
+[1]: https://lana-k.github.io/sqliteviz