Update docs/installation.asciidoc

Author: szabosteve

docs/installation.asciidoc

@@ -3,7 +3,7 @@
 
 Elasticsearch-php only has three requirements that you need to pay attention:
 
-* PHP 7.0.0 or higher
+* PHP 7.1.0 or higher
 * http://getcomposer.org[Composer]
 * http://php.net/manual/en/book.curl.php[ext-curl]: the Libcurl extension for 
   PHP (see note below)
@@ -98,4 +98,4 @@ against the REST specifications. This is a rather large download for
 non-developers, hence the --no-dev flag.
 
 If you wish to contribute to the development of this library, just omit the 
-`--no-dev` flag to be able to run tests.
+`--no-dev` flag to be able to run tests.