Replace master with {branch} in docs

Author: ezimuel

docs/community.asciidoc

@@ -151,6 +151,6 @@ _____________________
 This helper is a light library which wrap the official client elasticsearch-php. 
 It will help you to manage your ES Indices with no downtime. This helper 
 implements the philosophy described in the 
-https://www.elastic.co/guide/en/elasticsearch/guide/master/index-aliases.html[official documentation]
+https://www.elastic.co/guide/en/elasticsearch/guide/{branch}/index-aliases.html[official documentation]
 which can be summarized in a few words : *use alias instead of index directly*.
 _____________________

docs/release-notes.asciidoc

@@ -255,7 +255,7 @@
   the phpdoc section (for example, 
   https://github.com/elastic/elasticsearch-php/blob/master/src/Elasticsearch/Client.php[$client->rankEval()]). 
   For more information read the 
-  https://www.elastic.co/guide/en/elasticsearch/client/php-api/master/experimental_and_beta_apis.html[experimental and beta APIs] 
+  https://www.elastic.co/guide/en/elasticsearch/client/php-api/{branch}/experimental_and_beta_apis.html[experimental and beta APIs] 
   section in the documentation. 
   https://github.com/elastic/elasticsearch-php/pull/966[#966]
 * Removed `AlreadyExpiredException` since it has been removed