replace highlight.js EOL warning in changelog by title

[jelhan]

Highlight.js has already been upgraded to a recent version:

ember-keyboard/yarn.lock

Lines 7238 to 7246 in e95d348

	highlight.js@^10.7.1:
	version "10.7.3"
	resolved "https://registry.yarnpkg.com/highlight.js/-/highlight.js-10.7.3.tgz#697272e3991356e40c3cac566a74eef681756531"
	integrity sha512-tzcUFauisWKNHaRkN4Wjl/ZA07gENAjFl3J/c480dprkGTg5EQstgaNFqBfUqCq54kZRIEcreTsAgF/m2quD7A==
	highlight.js@^11.5.0:
	version "11.5.0"
	resolved "https://registry.yarnpkg.com/highlight.js/-/highlight.js-11.5.0.tgz#00abb7ed926491adbdabc93a4f3fd2b88b451b4a"
	integrity sha512-SM6WDj5/C+VfIY8pZ6yW6Xa0Fm1tniYVYWYW1Q/DcMnISZFrC3aQAZZZFAAZtybKNrGId3p/DNbFTtcTXXgYBw==

Let's remove the annoying warning as well from changelog.

While doing so I noticed that the changelog does not have a title yet. I added one.

[SergeAstapov]

@jelhan Thank you!