Freeze Functionbeat docs at 8.15

conf.yaml

@@ -2279,7 +2279,7 @@ contents:
             prefix:     en/beats/functionbeat
             current:    *stackcurrent
             index:      x-pack/functionbeat/docs/index.asciidoc
-            branches:   [ {main: master}, 8.x, 8.16, 8.15, 8.14, 8.13, 8.12, 8.11, 8.10, 8.9, 8.8, 8.7, 8.6, 8.5, 8.4, 8.3, 8.2, 8.1, 8.0, 7.17, 7.16, 7.15, 7.14, 7.13, 7.12, 7.11, 7.10, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7.3, 7.2, 7.1, 7.0, 6.8, 6.7, 6.6, 6.5 ]
+            branches:   [ 8.15, 8.14, 8.13, 8.12, 8.11, 8.10, 8.9, 8.8, 8.7, 8.6, 8.5, 8.4, 8.3, 8.2, 8.1, 8.0, 7.17, 7.16, 7.15, 7.14, 7.13, 7.12, 7.11, 7.10, 7.9, 7.8, 7.7, 7.6, 7.5, 7.4, 7.3, 7.2, 7.1, 7.0, 6.8, 6.7, 6.6, 6.5 ]
             chunk:      1
             tags:       Functionbeat/Reference
             respect_edit_url_overrides: true