General: Improve terminology used when referring to installations of WordPress and its extensions.

"Install" is not a noun, and while it might be acceptable to use the verb as a noun, it is not correct. Using the correct
noun, "installation", increases clarity, especially for non-native English speakers.

This change fixes the usage in user-facing text and in developer documentation.

Fixes #41620

Built from https://develop.svn.wordpress.org/trunk@41289


git-svn-id: http://core.svn.wordpress.org/trunk@41129 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/translation-install.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * WordPress Translation Install Administration API
+ * WordPress Translation Installation Administration API
  *
  * @package WordPress
  * @subpackage Administration
@@ -24,7 +24,7 @@ function translations_api( $type, $args = null ) {
 	}
 
 	/**
-	 * Allows a plugin to override the WordPress.org Translation Install API entirely.
+	 * Allows a plugin to override the WordPress.org Translation Installation API entirely.
 	 *
 	 * @since 4.0.0
 	 *
@@ -93,7 +93,7 @@ function translations_api( $type, $args = null ) {
 	}
 
 	/**
-	 * Filters the Translation Install API response results.
+	 * Filters the Translation Installation API response results.
 	 *
 	 * @since 4.0.0
 	 *