add note on how to use tika

doc/README.Converters

@@ -27,6 +27,12 @@ text/html
 Many office formats
   unoconv -d document -f txt --stdout '%s'
 
+Apache Tika is another option for creating plain text from various document
+types. Just use curl to send the document to your tika server and get the
+plain text in return.
+
+curl -s -T '%s' http://localhost:9998/tika --header 'Accept: text/plain'
+
 Conversion to pdf for pdf preview
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