[Update] Add additional instruction to the TSDB update process

[zeroallox]

It should be noted that after user installs or runs the latest version of TSDB / the docker image that they then need to use the psql console to do the update.

Something simple like:

After the new binaries have been installed, open the psql console utility and log in:
psql -U postgres -X

Switch to your TSDB database:
\c DATABASE-NAME

Run the update command:
ALTER EXTENSION timescaledb UPDATE;

Verify the update has been applied:
\dx

Emphasize that user needs to specifically switch to each database using \c db and run the ALTER EXT command. It is not a global "update all things" operation.

Location(s)
https://docs.timescale.com/latest/update-timescaledb/update-docker
https://docs.timescale.com/latest/update-timescaledb/update-tsdb-2

How soon is this needed?
Soon-ish as 2.0 is the new fancy release!

[jonatas]

Very good addition @zeroallox! I think a lot of people have the same issue, thinking that extensions are global, but we need to enable them. I'll make sure we add this detail to our docs roadmap.