Add system default location in FILES

And rephrase existing paragraphs.

docs/source/man_sbws.rst

@@ -69,32 +69,39 @@ sbws cleanup
 FILES
 -----
 
-$HOME/.sbws.ini
-   Default location for the sbws user configuration file.
+In the following list, the first path is the default location when running
+**sbws** as an script, the second path is the default location when running
+**sbws** as a system service.
 
-$HOME/.sbws
-   Default sbws home, where it stores measurement data files,
-   bandwidth list files and tor process data.
+**$HOME/.sbws.ini** or **/etc/sbws/sbws.ini**
+   Location where **sbws** searchs for a custom configuration file, when the
+   option **--config** is not provided.
 
-$HOME/.sbws/datadir
-   Default location for the raw results generated by the ``sbws scanner``.
-   Other commands (such as ``generate`` and ``stats``) read results from the
-   files in this directory.
+**$HOME/.sbws** or **/var/lib/sbws**
+   Location where **sbws** writes/reads measurement data files,
+   bandwidth list files and **tor** process data.
 
-$HOME/.sbws/log
-   Default location for the logs files generated by all ``sbws`` commands,
-   when logging to a file is configured (see **sbws.ini**).
+   Under this directory, **sbws** creates the following subdirectories:
 
-$HOME/.sbws/v3bw
-   Default location for the bandwidth files generated by the command
-   ``sbws generate``. These are the files read by the Tor directory
-   authorities.
+    datadir
+       Raw results generated by the ``sbws scanner``.
+       Other commands (such as ``generate`` and ``stats``) read results from
+       this directory.
 
-$HOME/.sbws/state.dat
-   A file for storing state needed between ``sbws`` commands.
+    log
+       Log files generated by ``sbws``, when logging to a file is configured
+       (see **sbws.ini**).
 
-$XDG_RUNTIME_DIR/sbws
-  Runtime directory for the tor process launched by ``sbws scanner``.
+    v3bw
+       Bandwidth files generated by ``sbws generate``. These are the files
+       read by the Tor directory authorities.
+
+    tor
+       Data generated by the **tor** process launched by **sbws**.
+
+**$HOME/.sbws/tor** or **/run/sbws/tor**
+  Location where the **tor** process launched by ``sbws scanner`` stores
+  temporal files, like Unix domain sockets.
 
 SEE ALSO
 ---------