Accessibility: Text Changes: Use sentence case for the word Error in various error messages, instead of all caps.

Using all caps should be avoided for better readability and because screen readers may pronounce all-caps words as abbreviations.

Props afercia, ryokuhi, sabernhardt, garrett-eclipse.
See #47656, #43037, #42945.
Built from https://develop.svn.wordpress.org/trunk@47156


git-svn-id: http://core.svn.wordpress.org/trunk@46956 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/load.php

@@ -489,7 +489,7 @@ function wp_set_wpdb_vars() {
 		wp_die(
 			sprintf(
 				/* translators: 1: $table_prefix, 2: wp-config.php */
-				__( '<strong>ERROR</strong>: %1$s in %2$s can only contain numbers, letters, and underscores.' ),
+				__( '<strong>Error</strong>: %1$s in %2$s can only contain numbers, letters, and underscores.' ),
 				'<code>$table_prefix</code>',
 				'<code>wp-config.php</code>'
 			)