Document db settings

Author: eahlberg

README.md

@@ -1,10 +1,8 @@
 # Tete time tracker
 
-- Basic CLI for time tracking: start, stop and list timers
-- Persistence using sqlite
-- Only one timer at a time
-- Optionally specify the database location by setting the environment variable
-  `TETE_DB_LOCATION`
+- Basic CLI for time tracking: start, stop and list timers.
+- Persistence using sqlite. The default DB location is at `$XDG_DATA_HOME/tete`but can be optionally specified by setting the environment variable `TETE_DB_DIR`.
+- Only one timer at a time.
 
 ## Run tests
 ```