Fixed plugin docs links to dir layouts

docs/plugins/plugin-script.asciidoc

@@ -3,8 +3,11 @@
 
 The `plugin` script is used to install, list, and remove plugins. It is
 located in the `$ES_HOME/bin` directory by default but it may be in a
-{ref}/setup-dir-layout.html[different location] if you installed Elasticsearch
-with an RPM or deb package.
+different location depending on which Elasticsearch package you installed:
+
+* {ref}/zip-targz.html#zip-targz-layout[Directory layout of `.zip` and `.tar.gz` archives]
+* {ref}/deb.html#deb-layout[Directory layout of Debian package]
+* {ref}/rpm.html#rpm-layout[Directory layout of RPM]
 
 Run the following command to get usage instructions:
 
@@ -208,7 +211,7 @@ On Windows, they need to be added to the `JAVA_OPTS` environment variable:
 
 [source,shell]
 -----------------------------------
-set JAVA_OPTS="-DproxyHost=host_name -DproxyPort=port_number"
+set ES_JAVA_OPTS="-DproxyHost=host_name -DproxyPort=port_number"
 bin/elasticsearch-plugin install mobz/elasticsearch-head
 -----------------------------------
 
@@ -225,8 +228,11 @@ following to the `elasticsearch.yml` config file:
 path.plugins: /path/to/custom/plugins/dir
 ---------------------
 
-The default location of the `plugins` directory depends on
-{ref}/setup-dir-layout.html[which package you install].
+The default location of the `plugins` directory depends on which package you install:
+
+* {ref}/zip-targz.html#zip-targz-layout[Directory layout of `.zip` and `.tar.gz` archives]
+* {ref}/deb.html#deb-layout[Directory layout of Debian package]
+* {ref}/rpm.html#rpm-layout[Directory layout of RPM]
 
 [float]
 === Mandatory Plugins