Add example with config dir set to: ~/.config/did/

This should provide a clear guidance for those who prefer to
keep their home directory clean and partially resolves #43.

docs/config.rst

@@ -4,12 +4,17 @@
 ==============
 
 The config file ``~/.did/config`` is used to store both general
-settings and configuration of individual reports. You can use the 
-``DID_CONFIG`` environment variable to override the default config
-directory ``~/.did`` and use your custom location instead. Command
-line option ``--config`` allows to select a different config file
-from the config directory. This can serve as a kind of a profile
-and is especially useful if you need to gather team reports.
+settings and configuration of individual reports. Command line
+option ``--config`` allows to select a different config file from
+the config directory. This can serve as a kind of a profile and is
+especially useful for gathering team reports.
+
+Use the ``DID_CONFIG`` environment variable to override the
+default config directory ``~/.did`` and use your custom location
+instead. For example if you prefer to keep you home directory
+clean you might want to add the following line into ``.bashrc``::
+
+    export DID_CONFIG=~/.config/did/
 
 
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