Fix for changed default when reading in timezone naive data: we no lo…

…nger assume utc, but raise instead (see PR #521)

Signed-off-by: F.N. Claessen <felix@seita.nl>

documentation/tut/toy-example-from-scratch.rst

@@ -211,12 +211,12 @@ This is time series data, in FlexMeasures we call "beliefs". Beliefs can also be
 
 .. code-block:: console
 
-    $ flexmeasures add beliefs --sensor-id 3 --source toy-user prices-tomorrow.csv
+    $ flexmeasures add beliefs --sensor-id 3 --source toy-user prices-tomorrow.csv --timezone utc
     Successfully created beliefs
 
 In FlexMeasures, all beliefs have a data source. Here, we use the username of the user we created earlier. We could also pass a user ID, or the name of a new data source we want to use for CLI scripts.
 
-.. note:: Attention: We created and imported prices where the times have no time zone component! That happens a lot. FlexMeasures will then interpret them as UTC time. So if you are in Amsterdam time, the start time for the first price, when expressed in your time zone, is actually `2022-03-03 01:00:00+01:00`.
+.. note:: Attention: We created and imported prices where the times have no time zone component! That happens a lot. Here, we localized the data to UTC time. So if you are in Amsterdam time, the start time for the first price, when expressed in your time zone, is actually `2022-03-03 01:00:00+01:00`.
 
 Let's look at the price data we just loaded: