I18N: Provide gettext context to disambiguate translation strings for "Notes".

"Notes" translation string is used in both the Notes features and in the Link Manager, and they can have different meaning in some Locales, like in German for example. This changeset helps disambuguating these different contexts.

Props westonruter, dmsnell, johnbillion.
Fixes #64980.



git-svn-id: https://develop.svn.wordpress.org/trunk@62185 602fd350-edb4-49c9-b593-d223f7449a82