doc/cephadm: Small improvements in services/tracing.rst

doc/cephadm: Small improvements in services/tracing.rst

Use ref instead of a full URL link and add label for it in
doc/jaegertracing/index.rst.

Capitalize "Ceph", "Jaeger", "ElasticSearch" consistently.
Start sentences with capital case consistently.
Fix a typo.

Wrap lines a bit before column 80.

Use an ordered list instead of hardcoding list numbers in separate
paragraphs.

Don't use ordered list for items that do not both fit under the text
paragraph introducing the list.
Rewrite the sentences to be more consistent and hopefully more correct.

Add articles that I believe should be there, also for consistency with
the previous paragraph.

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