indexStoreDocText config variable, fix terms and conditions when we store the doc text or not

src/sampleconf/recoll.conf

@@ -233,16 +233,26 @@ indexStripChars = 1
 
 # <var name="indexStoreDocText" type="bool"><brief>Decide if we store the
 # documents' text content in the index.</brief><descr>Storing the text
-# allows extracting snippets from it at query time, 
-# instead of building them from index position data. This Has become
-# necessary for versions of Xapian 1.6, which have dropped support
-# for the chert index format, and adopted a setup which renders our
-# use of positions list unacceptably slow in cases. 'raw' text here
-# means that the text is not stripped of upper-case, diacritics, or
-# punctuation signs. It is still translated from its original format
-# to UTF-8 plain text. This increases the index size by 10-20% typically,
-# but also allows for nicer snippets, so it may be worth enabling it even
-# if not strictly needed for performance if you can afford the space.
+# allows extracting snippets from it at query time, instead of building
+# them from index position data.
+#
+# Newer Xapian index formats have rendered our use of positions list
+# unacceptably slow in some cases. The last Xapian index format with good
+# performance for the old method is Chert, which is default for 1.2, still
+# supported but not default in 1.4 and will be dropped in 1.6.
+#
+# The document text is translated from its original format to UTF-8 plain
+# text, but not stripped of upper-case, diacritics, or punctuation
+# signs. Storing it increases the index size by 10-20% typically, but also
+# allows for nicer snippets, so it may be worth enabling it even if not
+# strictly needed for performance if you can afford the space.
+#
+# The variable only has an effect when creating an index, tested as
+# xapiandb directory not existing. Its exact effect depends on the Xapian
+# version. For Xapian 1.2, you can force the new method by setting the
+# variable to 1. For Xapian 1.4, the Chert format will be used, and the text
+# will not be stored if the variable is not set or set to 0. For later
+# Xapian versions, the variable does nothing, the text is always stored.
 # </desc></var>
 indexStoreDocText = 0