add config option

services-user-guide/python.md

@@ -13,3 +13,30 @@ The url to use the CachingProxy is: https://pypi.psi.ch/simple:
 
 You can manually specify the url while using the `pip` command as follows:
 pip install --index-url=https://pypi.psi.ch/simple pandas
+
+
+To fix the default url for your user to the proxy you can create the following config file within your users home directory:
+
+```bash
+% cat ~/.config/pip/pip.conf 
+[global]
+timeout = 60
+index-url = https://pypi.psi.ch/simple
+```
+
+To check whether your pip client is using this address you can simply issue a:
+```
+pip install -h
+```
+
+Check whats written in the descripiton of the option --index-url:
+
+```
+% pip install -h | grep -A5 index-url 
+  -i, --index-url <url>       Base URL of the Python Package Index (default
+                              https://pypi.psi.ch/simple). This should point
+                              to a repository compliant with PEP 503 (the
+                              simple repository API) or a local directory laid
+                              out in the same format.
+...
+```