Filter mixer docs from related content sections (#9563)

* wip

* update keywords for observability pages

* switch to front-matter based approach

content/en/blog/2017/adapter-model/index.md

@@ -8,6 +8,7 @@ keywords: [adapters,mixer,policies,telemetry]
 aliases:
     - /blog/mixer-adapter-model.html
 target_release: 0.2
+exclude_from_see_also: true
 ---
 
 Istio 0.2 introduced a new Mixer adapter model which is intended to increase Mixer’s flexibility to address a varied set of infrastructure backends. This post intends to put the adapter model in context and explain how it works.

content/en/blog/2017/mixer-spof-myth/index.md

@@ -9,6 +9,7 @@ aliases:
     - /blog/posts/2017/mixer-spof-myth.html
     - /blog/mixer-spof-myth.html
 target_release: 0.3
+exclude_from_see_also: true
 ---
 
 As [Mixer](https://istio.io/v1.6/docs/reference/config/policy-and-telemetry/) is in the request path, it is natural to question how it impacts

content/en/docs/concepts/observability/index.md

@@ -2,7 +2,7 @@
 title: Observability
 description: Describes the telemetry and monitoring features provided by Istio.
 weight: 40
-keywords: [policies,telemetry,control,config]
+keywords: [telemetry,metrics,logs,tracing]
 aliases:
     - /docs/concepts/policy-and-control/mixer.html
     - /docs/concepts/policy-and-control/mixer-config.html

content/en/docs/reference/config/metrics/index.md

@@ -2,6 +2,7 @@
 title: Istio Standard Metrics
 description: Istio standard metrics exported by Istio telemetry.
 weight: 50
+keywords: [telemetry,metrics]
 owner: istio/wg-user-experience-maintainers
 test: n/a
 aliases:

content/en/docs/tasks/observability/logs/access-log/index.md

@@ -2,7 +2,7 @@
 title: Getting Envoy's Access Logs
 description: This task shows you how to configure Envoy proxies to print access logs to their standard output.
 weight: 10
-keywords: [telemetry]
+keywords: [telemetry,logs]
 aliases:
     - /docs/tasks/telemetry/access-log
     - /docs/tasks/telemetry/logs/access-log/

layouts/partials/primary_bottom.html

@@ -3,8 +3,10 @@
 {{ $skipPageNav := .Scratch.Get "skipPageNav" }}
 
             {{ if .Scratch.Get "seeAlso" }}
-                {{ $related := .Site.RegularPages.Related . | first 6 }}
-                {{ with $related }}
+                {{ $related := .Site.RegularPages.Related . }}
+                {{ $excludes := where $related "Params.exclude_from_see_also" true }}
+                {{ $seeAlso := $related | complement $excludes | first 6 }}
+                {{ with $seeAlso }}
                     <nav id="see-also">
                         <h2>{{ i18n "see_also" }}</h2>