Add a limit for text analysis

modules/joex/src/main/resources/reference.conf

@@ -193,6 +193,18 @@ docspell.joex {
     }
   }
 
+  # Settings for text analysis
+  text-analysis {
+    # Maximum length of text to be analysed.
+    #
+    # All text to analyse must fit into RAM. A large document may take
+    # too much heap. Also, most important information is at the
+    # beginning of a document, so in most cases the first two pages
+    # should suffice. Default is 10000, which are about 2-3 pages
+    # (just a rough guess, of course).
+    max-length = 10000
+  }
+
   # Configuration for converting files into PDFs.
   #
   # Most of it is delegated to external tools, which can be configured