udpate mapped pages (#2248)

Author: colleenmcginnis

docs/reference/upgrading-4-x.md

@@ -1,6 +1,6 @@
 ---
 mapped_pages:
-  - https://www.elastic.co/guide/en/apm/agent/python/current/upgrading-4-x.html
+  - https://www.elastic.co/guide/en/apm/agent/python/current/upgrading-4.x.html
 ---
 
 # Upgrading to version 4 of the agent [upgrading-4-x]

docs/reference/upgrading-5-x.md

@@ -1,6 +1,6 @@
 ---
 mapped_pages:
-  - https://www.elastic.co/guide/en/apm/agent/python/current/upgrading-5-x.html
+  - https://www.elastic.co/guide/en/apm/agent/python/current/upgrading-5.x.html
 ---
 
 # Upgrading to version 5 of the agent [upgrading-5-x]

docs/reference/upgrading-6-x.md

@@ -1,6 +1,6 @@
 ---
 mapped_pages:
-  - https://www.elastic.co/guide/en/apm/agent/python/current/upgrading-6-x.html
+  - https://www.elastic.co/guide/en/apm/agent/python/current/upgrading-6.x.html
 ---
 
 # Upgrading to version 6 of the agent [upgrading-6-x]

docs/release-notes/index.md

@@ -2,15 +2,16 @@
 navigation_title: "Elastic APM Python Agent"
 mapped_pages:
   - https://www.elastic.co/guide/en/apm/agent/python/current/release-notes-6.x.html
+  - https://www.elastic.co/guide/en/apm/agent/python/current/index.html
 ---
 
 # Elastic APM Python Agent release notes [elastic-apm-python-agent-release-notes]
 
-Review the changes, fixes, and more in each version of Elastic APM Python Agent. 
+Review the changes, fixes, and more in each version of Elastic APM Python Agent.
 
 To check for security updates, go to [Security announcements for the Elastic stack](https://discuss.elastic.co/c/announcements/security-announcements/31).
 
-% Release notes includes only features, enhancements, and fixes. Add breaking changes, deprecations, and known issues to the applicable release notes sections. 
+% Release notes includes only features, enhancements, and fixes. Add breaking changes, deprecations, and known issues to the applicable release notes sections.
 
 % ## version.next [elastic-apm-python-agent-versionext-release-notes]
 % **Release date:** Month day, year