deploying docs: docs: Detail how to use Jinja parameters (#20308)

We expand the example to show how to use the `from_dttm` and `to_dttm`
Jinja parameters in logic blocks (e.g. `{% if … %}`) and underline when
to use the double braces and when not to.

All this because, well, *one* could lost quite an extensive amount of
time figuring this all out (-_-")

Signed-off-by: Étienne Boisseau-Sierra <etienne.boisseau-sierra@unipart.io> (apache/superset@80be1ce6575fdcef7f47b8136c9b91bd7f9ad5d7)
81 files changed