docs(core): remove non-features from changelog (#27600)

Remove:
- Automatically update Nx
- Monorepo World Conference Speakers Announced

From changelog page, since those are not new features in 19.5

Author: isaacplmann

docs/changelog/19_5_0.md

@@ -20,7 +20,5 @@ Read the [blogpost](/blog/nx-19-5-adds-stackblitz-new-features-and-more) for ful
 {% card title="Experimental: Gradle Test Atomization" type="document" url="/blog/nx-19-5-adds-stackblitz-new-features-and-more#experimental-gradle-test-atomization" /%}
 {% card title="Experimental: Nx Release Adds Version Plans Support" type="document" url="/blog/nx-19-5-adds-stackblitz-new-features-and-more#experimental-nx-release-adds-version-plans-support" /%}
 {% card title="Support for React 19 (rc) and Angular 18.1" type="document" url="/blog/nx-19-5-adds-stackblitz-new-features-and-more#support-for-react-19-rc-and-angular-181" /%}
-{% card title="Automatically Update Nx" type="document" url="/blog/nx-19-5-adds-stackblitz-new-features-and-more#automatically-update-nx" /%}
-{% card title="Monorepo World Conference Speakers Announced!!" type="document" url="/blog/nx-19-5-adds-stackblitz-new-features-and-more#monorepo-world-conference-speakers-announced" /%}
 
 {% /cards %}