Update User Guide.md

Author: ldn-softdev

User Guide.md

@@ -34,7 +34,7 @@
      * [Displaying walks with labels (`-l`)](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#displaying-walks-with-labels)
      * [Wrapping resulted walks to JSON array (`-j`)](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#wrapping-resulted-walks-to-json-array)
      * [Interleaved walk processing](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#interleaved-walk-processing)
-     * [Aggregating walks](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#aggregating-walks)
+     * [Aggregating walks (`-nn`)](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#aggregating-walks)
      * [Wrapping walked entries into a JSON object (`-jj`)](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#wrapping-walked-entries-into-a-json-object)
      * [Extracting labeled values (`-ll`)](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#extracting-labeled-values)
      * [Succinct walk-path syntax (`-x`,`-y`)](https://github.com/ldn-softdev/jtc/blob/master/User%20Guide.md#succinct-walk-path-syntax)