Improve Postman achievement description

[FloEdelmann]

As noticed in #5638 (comment), the current description for the Postman achievement doesn't match the quests that count towards it:

StreetComplete/app/src/main/res/values/strings.xml

Line 507 in f4f7dcf

<string name="achievement_postman_solved_X">You helped to locate %d addresses!\nThis data is essential not only for the mail carrier but also for any navigation system.</string>

In particular, the postbox quests¹ and new parcel locker quests² don't match the description, while the address quests³ and the address overlay do.

We should find a better description (and maybe also achievement title? → see #3009) that matches all these quests. Suggestions are welcome!

Footnotes

1. AddPostboxRoyalCypher, AddPostboxRef, AddPostboxCollectionTimes ↩

2. AddParcelLockerBrand, AddParcelLockerMailIn, AddParcelLockerPickup ↩

3. AddRoadName, AddHousenumber, AddAddressStreet ↩

[mnalis]

perhaps something simple along the lines of:

- You helped to locate %d addresses!
+ You helped to locate %d addresses and other postal amenities!