transifex: ldap expert ttl description

[voroyam]

german:

Speichere Time-To-Live zwischen 600 in Sekunden.

english:

Cache Time-To-Live 600 in seconds.

The German translation sounds weird. I know the German verb zwischenspeichern but it's rarely used and looks out of place here. Also the following number indicates that something has to be cached between the following number and ... some other number.

I suggest removing the "zwischen" or replacing it with something better