Further instructions for time zone profile setting

[pascalwittler]

The profile setting "Time zone" ("Zeitzone" in screenshot [1] below) is currently implemented as a free text input with no further instructions so people might wonder (or just guess) what to enter there.

Example: If you live in Karlsruhe, Germany (UTC+01:00 in winter and UTC+02:00 in summer), you could at least enter:

• Karlsruhe
• Karlsruhe, Germany
• Berlin
• Europe/Berlin
• Central Europe / Mitteleuropa / Zentraleuropa
• Central European Time / CET / Central European Summer Time / CEST
• Mitteleuropäsische Zeit / MEZ / Mitteleuropäsische Sommerzeit / MESZ
• +1 / +2
• +01:00 / +02:00
• UTC+01:00 / UTC+02:00
• UTC+1 / UTC+2
• +60 / +120

A drop-down <select> menu, a <datalist> for input suggestions, further instructions or at least an example would be nice!

[1] Time zone ("Zeitzone") as free text input in profile settings

Possible overlap with #1834