Issue #2578989 by ifrik, alvar0hurtad0, jhodgdon, Bojhan, snehi, mairi,...

Issue #2578989 by ifrik, alvar0hurtad0, jhodgdon, Bojhan, snehi, mairi, rachel_norfolk: Update link descriptions on the Configuration page that are not correct for D8

core/modules/aggregator/aggregator.links.menu.yml

 aggregator.admin_overview:
   title: 'Feed aggregator'
-  description: 'Configure which content your site aggregates from other sites, how often it polls them, and how they''re categorized.'
+  description: 'Add feeds or import OPMLs to gather external content and configure how often they are updated.'
   route_name: aggregator.admin_overview
   parent: system.admin_config_services
   weight: 10

core/modules/language/language.links.menu.yml

 entity.configurable_language.collection:
   title: Languages
-  description: 'Configure languages for content and the user interface.'
+  description: 'Configure languages for content, interface, and configuration.'
   route_name: entity.configurable_language.collection
   parent: system.admin_config_regional
 language.content_settings_page:

core/modules/path/path.links.menu.yml

 path.admin_overview:
   title: 'URL aliases'
-  description: 'Change your site''s URL paths by aliasing them.'
+  description: 'Add custom URLs to existing paths.'
   route_name: path.admin_overview
   parent: system.admin_config_search
   weight: -5

core/modules/simpletest/simpletest.links.menu.yml

 simpletest.test_form:
   title: Testing
-  description: 'Run tests against Drupal core and your modules. These tests help assure that your site code is working as designed.'
+  description: 'Run tests against the site''s core code and enabled modules to review your code.'
   route_name: simpletest.test_form
   parent: system.admin_config_development
   weight: -5

core/modules/user/user.links.menu.yml

@@ -24,6 +24,6 @@ user.admin_index:
 entity.user.admin_form:
   title: 'Account settings'
   parent: user.admin_index
-  description: 'Configure default behavior of users, including registration requirements, emails, and fields.'
+  description: 'Configure default user account settings, including fields, registration requirements, and email messages.'
   weight: -10
   route_name: entity.user.admin_form