[README] add missing v and use latest versions

[nellicus]

Summary

Adds a missing 'v' in the metabase version that prevents the instructions from failing:

export METABASE_VERSION=0.47.2
export METABASE_CLICKHOUSE_DRIVER_VERSION=1.2.1

mkdir -p mb/plugins && cd mb
curl -o metabase.jar https://downloads.metabase.com/$METABASE_VERSION/metabase.jar
curl -L -o plugins/ch.jar https://github.com/ClickHouse/metabase-clickhouse-driver/releases/download/$METABASE_CLICKHOUSE_DRIVER_VERSION/clickhouse.metabase-driver.jar
MB_PLUGINS_DIR=./plugins; java -jar metabase.jar
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   547  100   547    0     0   1179      0 --:--:-- --:--:-- --:--:--  1189
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100 1625k  100 1625k    0     0  2052k      0 --:--:-- --:--:-- --:--:-- 2052k
Error: Invalid or corrupt jarfile metabase.jar

Also updates the sample versions in use to current for both clickhouse driver and metabase jar

Plus some unintended github table reformatting.

Checklist

Delete items not relevant to your PR:

• [x] A human-readable description of the changes was provided to include in CHANGELOG

[slvrtrn]

thanks!