)

There were some last minute changes to ES|QL that will ship in 8.14 that
we need to take into account:

- [BUCKET is now an aggregation
function](elastic/elasticsearch#107272)
- [index names can no longer be escaped with backticks
](elastic/elasticsearch#108431)

I'm also including a change that translates `=` to `==` in WHERE
commands, and more useful error messages (map a syntax error to the
command where it occurred).

As BUCKET is often used for timeseries data and we replaced single and
double quotes around index names with backticks, this introduces a high
chance of generating syntactically invalid queries. This PR updates the
docs and examples and removes the correction from `"` and `'` to "`"

(cherry picked from commit 6004cad)