doc/radosgw: Cosmetic improvements in dynamicresharding.rst

doc/radosgw: Cosmetic improvements in dynamicresharding.rst

Make reference to config section a hyperlink.

Capitalization consistency: use title case in section titles, fix two
invalid capitalizations in text.

Promptify CLI example commands.

A JSON key-value pair is a "property" and not an "object".

Use an ordered list instead of inline code with hardcoded list numbers.

Use the American "canceled" (majority of occurrences in doc/) instead of
"cancelled".

Use admonitions instead of spelling out "Note:".
Clarify language on sharding cleanup for multisite.

Format JSON keys as inline code.

Indent example JSON output from radosgw-admin correctly (same as real
output) with 4 spaces.

Use colon instead of full stop at the end of text that describes the
following example command. Move admonition to after such example
command.

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