add link

services-user-guide/python.md

@@ -24,6 +24,9 @@ timeout = 60
 index-url = https://pypi.psi.ch/simple
 ```
 
+To change the default for the whole system edit: `/etc/pip.conf`
+(also see: https://pip.pypa.io/en/stable/topics/configuration/#location) 
+
 To check whether your pip client is using this address you can simply issue a:
 ```
 pip install -h
@@ -39,4 +42,12 @@ Check whats written in the descripiton of the option --index-url:
                               simple repository API) or a local directory laid
                               out in the same format.
 ...
+```
+
+or do a `pip config list`
+```
+% pip config list
+global.index-url='https://pypi.psi.ch/simple'
+global.timeout='60'
+
 ```