doc/cephadm/services: remove excess rendered indentation in osd.rst

doc/cephadm/services: remove excess rendered indentation in osd.rst

Start bash command blocks at the left margin, removing
excessive padding/indentation that would render the
block too much towards the right.

At the same time ident the source consistently:
- Two spaces for command blocks and output blocks.
- Four spaces for notes, code blocks.

There seems to be no uniform style for this, sometimes
commands are indented with three spaces but it would
seem two spaces is common. In the end it all renders
the same I guess.

Signed-off-by: Ville Ojamo <14869000+bluikko@users.noreply.github.com>