[Update] Instructions for migrating data from existing PG table

[mfreed]

Our docs provides isntructions for migrating from the same database, but appears to have been written prior to the support for migrate_data in a hypertable. Specifically, it suggests creating a second table, then running INSERT INTO new_table SELECT * FROM old_table;

https://docs.timescale.com/latest/getting-started/migrating-data#same-db

We should update these instructions to instead just point at migrate_data feature/parameter of hypertables:

https://docs.timescale.com/latest/api#create_hypertable

[rept]

Definitely! Didn't know this was possible. Since this saves people from having to over dimension their machines in order to migrate. Is it also possible to immediately convert an existing table to a hypertable with compression as well?