updating docs with note on how to interpret replacedRegions property

source/extensionAuthor/messages.rst

@@ -32,9 +32,13 @@ Write
 .. include:: \..\messages\log\write.json
    :code: json
 
-.. NOTE:: The ``pattern`` property should be a JavaScript compatible `Regular Expression <https://en.wikipedia.org/wiki/Regular_expression>`_ representation of log messages that leverage `string interpolation <https://en.wikipedia.org/wiki/String_interpolation>`_. The purpose of this property is allow Glimpse clients to treat interpolated values specially, `as demonstrated on JSFiddle <https://jsfiddle.net/coc2yofo/12/>`_. 
+.. NOTE:: The ``replacedRegions`` property is used indicate sub-strings in a log messages that leveraged `string interpolation <https://en.wikipedia.org/wiki/String_interpolation>`_. 
+  The purpose of this property is to allow Glimpse clients to treat interpolated values specially, `as demonstrated 
+  on JSFiddle <https://jsfiddle.net/coc2yofo/12/>`_. 
 
-  Regular Expressions were chosen since they are `nearly universal <https://en.wikipedia.org/wiki/Comparison_of_regular_expression_engines#Language_features>`_ and can represent any interpolation format. (``%s``, ``{0}``, ``{1:d}``, ``{foo}``, ``$(bar)``, etc.)
+  ``replacedRegions`` is a JSON array of objects, where each object has a ``start`` property and an ``end`` property.  ``start`` 
+  represents the inclusive start of an interpolated region, and ``end`` represents the exclusive end of the interpolated region. 
+  i.e., ``end`` is the first position after the interpolated region. 
 
 MongoDB
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