use new URL for breaking-changes section.

Author: simitt

docs/installing-stack.asciidoc

@@ -17,7 +17,7 @@ Install the Elastic Stack products you want to use in the following order:
 . Kibana ({kibana-ref}/install.html[install])
 . Logstash ({logstash-ref}/installing-logstash.html[install])
 . Beats ({beats-ref}/getting-started.html[install instructions])
-. APM Server({apm-server-ref}/installing.html[install instructions])
+. APM Server ({apm-server-ref}/installing.html[install instructions])
 . Elasticsearch Hadoop ({hadoop-ref}/install.html[install instructions])
 
 Installing in this order ensures that the components each product depends

docs/upgrading-stack.asciidoc

@@ -45,7 +45,7 @@ and make the necessary changes so your code is compatible with {version}:
 +
 --
 ** {beats-ref}/breaking-changes.html[Beats {version} breaking changes]
-** {apm-server-ref}/upgrading.html#breaking-changes[APM Server {version} breaking changes]
+** {apm-server-ref}/breaking-changes.html[APM Server {version} breaking changes]
 ** {ref}/breaking-changes.html[Elasticsearch {version} breaking changes]
 ** {hadoop-ref}/breaking-changes.html[Elasticsearch Hadoop {version} breaking changes]
 ** {kibana-ref}/breaking-changes.html[Kibana {version} breaking changes]