[web] Documentation for the AddElementQuality tool.

web/content/docs/tools/model-preparation/add-element-quality/index.md

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+title = "Add element quality to mesh"
+author = "Thomas Fischer"
+
+[menu]
+  [menu.tools]
+    parent = "model-preparation"
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+
+The command line tool `AddElementQuality` adds a data array to the given mesh
+that holds for each element a value for the quality. The quality value depends
+on the choosen quality criterion. The available quality criteria are shown using
+the help argument on the command line. The resulting data arrays can be used to
+draw histograms or can be visually analyzed in the OGS Data Explorer or Paraview.