[Doc] Add Notes for *Create Topic*

[Anonymitaet]

Fix #4897

@cumtwwei @sijie could you please help review? Thank you

[Jennifer88huang-zz]

There is no language issue in the note.
A tiny suggestion: if you add the same note several times in a doc, it indicates the note is very important, it's better to add it in a general and obvious place once for all. It's easy to find and maintain.

[Anonymitaet]

@jennifer88huang thanks for your suggestion, while this note has been added for 3 documents and 5 places.
Since the note is pretty important and easily ignored when users creating topics, we'd better emphasis it and remind users in every "create topic" related section.

[sijie]

run cpp tests
run java8 tests

[sijie]

run cpp tests

[Anonymitaet]

@sijie could you please help merge this PR? Thank you