Bug 1919365 - use consistent capitalization for "Learn more" in settings page r=fluent-reviewers DONTBUILD

Differential Revision: https://phabricator.services.mozilla.com/D222515

browser/locales/en-US/browser/preferences/preferences.ftl

@@ -1213,7 +1213,7 @@ sitedata-cookies-exceptions =
 
 cookie-banner-blocker-header = Cookie Banner Blocker
 cookie-banner-blocker-description = When a site asks if they can use cookies in private browsing mode, { -brand-short-name } automatically refuses for you. Only on supported sites.
-cookie-banner-learn-more = Learn More
+cookie-banner-learn-more = Learn more
 cookie-banner-blocker-checkbox-label =
     .label = Automatically refuse cookie banners