Adding sw ver to template engine

src_docs/source/advanced.rst

@@ -99,4 +99,10 @@ These are the format keys available for use in the format.
    * - ${gravity-unit}
      - Gravity format, `G` or `P`
      - G
+   * - ${sw-ver}
+     - Software version
+     - 1.1.0
+   * - ${sw-rev}
+     - Software revision (git hash)
+     - ..e456743
 

src_docs/source/formula.rst

@@ -9,8 +9,31 @@ Create formula
 
 Here you can enter up to 10 values (angles + gravity) that is then used to create the formula. Angles equal to zero will be regarded as empty even if there is a gravity reading.
 
+When you submit the values the device will try create a forumla with increasing level of complexity. It will start
+with a order 2 formula and then try 3 and 4.
+
+Once the formula has been created it will validate the formula against the supplied angles/gravity and if there is a too
+high difference, it will fail. You can adjust the sensitivity under advanced settings if you have issues. 
+
+Under the Error Log you will also find hints to what problem the formula creator encountered. Here is an example:
+
+`CALC: Validation failed on angle 33.430000, deviation too large 5.86, formula order 4`
+
+`CALC: Validation failed on angle 33.430000, deviation too large 3.14, formula order 2`
+
+This means that the angle 33.43 had a deviation of 5.8 SG and since the default threashold is 3, it will fail. You 
+can also see that it has failed on that point in both a order 2 and 4 formula.
+
+.. image:: images/qa_1.png
+  :width: 400
+  :alt: Example of deviating value
+
+So in this case you can either increase the threashold or remove the angle that has an issue. You can also 
+use the graph on the calibration page to identify angles that is probably not correct.
+
 .. image:: images/formula2.png
   :width: 800
   :alt: Formula graph
 
 Once the formula is created a graph over the entered values and a simulation of the formula will give you a nice overview on how the formula will work.
+