[Taler] Manual mentions wrong section for AML_THRESHOLD

[Florian Jung]

Hi,

it's this time of the year again \o/.


The manual inaccurately tells me to add the AML_THRESHOLD to the 
[exchange] section[1], while the taler-exchange binary complains as follows:

2023-07-31T23:33:55.323050+0000 taler-exchange-httpd-29 ERROR 
Configuration fails to specify option `AML_THRESHOLD' in section `taler'!

And in fact, adding the line to the [taler] section (instead of 
[exchange]) does the trick.

Please fix the documentation accordingly, thanks <3.


Cheers and happy hacking,

Florian


[1] https://docs.taler.net/taler-exchange-manual.html#aml-triggers