Update whats_new.md

Author: kthyng

docs/whats_new.md

@@ -1,8 +1,14 @@
 # What's New
 
-## v2.1.0 (unreleased)
+## v3.0.0 (March 17, 2023)
 
 * Fixed a deprecation warning (https://github.com/matplotlib/cmocean/pull/86), by @neutrinoceros
 * Added CodeQL workflow (https://github.com/matplotlib/cmocean/pull/85), by bot
 * Changed master to main, by @kthyng
-* Added new CI workflows (testing, dependabot) and added codecov (https://github.com/matplotlib/cmocean/pull/88), by @kthyng
+* Added new CI workflows (testing, dependabot) and added codecov (https://github.com/matplotlib/cmocean/pull/88), by @kthyng
+* Updated URL for STOQS visualization example by @MBARIMike in #75
+* Update README: add cmocean usage in Julia by @ali-ramadhan in #77
+* [MOD] removal of 'figures' for savefig() commands by @jehyunlee in #80
+* Document dependencies by @adamjstewart in #78
+* add r package cmocean by @japhir in #81
+* ENH: work around pending deprecation warnings in MPL by @neutrinoceros in #86