Whats-New updates for v3.16.0rc0 . (#7238)

* Whats-New updates for v3.16.0rc0 .

* replace placeholder text

* update path to 3.16.rst

* change include reference

* change path

* add link to a highlight entry

Whats-New updates for v3.15.0 . (#7018)

Whats-New updates for v3.15.0rc0 . (#6986)

Whats-New updates for v3.14.1 . (#6846)

* Whats-New updates for v3.14.1 .

* fix whatsnew

Whats-New updates for v3.14.0 . (#6800)

V3.14.x updates (#6780)

* update whatsnew for 3.14 release candidate

* address comments

* update index references

* remove template

* fix typo

Whats new updates for v3.13.1 . (#6670)

Whats new updates for v3.12.3 . (#6668)

whatsnew updates for v3.13.0 (#6616)

whatsnew updates for v3.13.0rc0 (#6583)

* whatsnew updates for v3.13.0rc0

* fix whatsnew entry