Issue #3506177 by juandhr: Modify support mentions for Drupal core's search in README

Issue #3506177 by juandhr: Modify support mentions for Drupal core's search in README

Replace lines 26 and 27 in README.md:

No other modules are required; we're supporting Drupal Core's search as a source for creating facets.

With:

Search API is required: Facets only supports Search API as a source for creating facets. Drupal Core's search is no longer supported as a source for facets.

Closes Issue #3506177

README.md

@@ -9,7 +9,7 @@ For a full description of the module, visit the
 Submit bug reports and feature suggestions, or track changes in the
 [issue queue](https://www.drupal.org/project/issues/facets).
 
-## Table of contents 
+## Table of contents
 
 - Requirements
 - Recommended Modules
@@ -23,8 +23,8 @@ Submit bug reports and feature suggestions, or track changes in the
 
 ## Requirements
 
-No other modules are required; we're supporting Drupal Core's search as a
-source for creating facets.
+Search API is required: Facets only supports Search API as a source for creating
+facets. Drupal Core's search is no longer supported as a source for facets.
 
 
 ## Recommended Modules