Fixed docs rendering of plugin-descriptor.properties in plugin author docs

docs/plugins/authors.asciidoc

@@ -31,7 +31,7 @@ All plugin files must be contained in a directory called `elasticsearch`.
 All plugins must contain a file called `plugin-descriptor.properties` in the folder named `elasticsearch`.
 The format for this file is described in detail in this example:
 
-["source","properties",subs="attributes"]
+["source","properties"]
 --------------------------------------------------
 include::{plugin-properties-files}/plugin-descriptor.properties[]
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