Is your feature request related to a problem? Please describe.
The problem I encountered is that I tried to follow the setup described in the developers_md and it did not work as intended. The picker was empty instead of showing my values. This has been solved by changing the table provided to 'entry_marker' to be indexed by integers. This worked.

Describe the solution you'd like
I would like the documentation to be altered such that this requirement is mentioned.
Describe alternatives you've considered
One could also alter the picker behavior such that this works on non-integer-indexed tables. I think it should work on these, but I am fine with adding documentation.

Additional context
I would be open to contributing a suggestion, I have had a small contribution to telescope in the past and know my way around the process.