Fixing #5537: Adding mandatory target annotation and their units. (#5629

)

* Issue# #5537: Update autoscaling-metrics.md to add the mandatory target values

As per issue  #5537,  creating this PR for adding mandatory target annotation.

* Fixing #5537: Implementing PR comments

* Fixing #5634: Update home.html

* Reverting the commit for other issue

Reverting the commit for other issue so that I can fork one branch per issue

* Fixing #5537: Adding review comments

* Fixing#5537: Updating note formatting

* Update autoscaling-metrics.md

* Update autoscaling-metrics.md

* Update autoscaling-metrics.md

* Update autoscaling-metrics.md

docs/serving/autoscaling/autoscaling-metrics.md

@@ -32,7 +32,10 @@ For more information about KPA and HPA, see the documentation on [Supported Auto
         metadata:
           annotations:
             autoscaling.knative.dev/metric: "concurrency"
+            autoscaling.knative.dev/target-utilization-percentage: "70" 
     ```
+    !!! note
+        The `autoscaling.knative.dev/target-utilization-percentage` annotation for "Concurrency" specifies a percentage value
 
 === "Requests per second"
 
@@ -47,7 +50,10 @@ For more information about KPA and HPA, see the documentation on [Supported Auto
         metadata:
           annotations:
             autoscaling.knative.dev/metric: "rps"
+            autoscaling.knative.dev/target: "150"
     ```
+    !!! note
+        The `autoscaling.knative.dev/target` annotation for "Requests per second" specifies an integer value
 
 === "CPU"
 
@@ -63,7 +69,10 @@ For more information about KPA and HPA, see the documentation on [Supported Auto
           annotations:
             autoscaling.knative.dev/class: "hpa.autoscaling.knative.dev"
             autoscaling.knative.dev/metric: "cpu"
+            autoscaling.knative.dev/target: "100"
     ```
+    !!! note
+        The `autoscaling.knative.dev/target` annotation for "CPU" specifies the integer value in millicore
 
 === "Memory"
 
@@ -79,7 +88,10 @@ For more information about KPA and HPA, see the documentation on [Supported Auto
           annotations:
             autoscaling.knative.dev/class: "hpa.autoscaling.knative.dev"
             autoscaling.knative.dev/metric: "memory"
+            autoscaling.knative.dev/target: "75"
     ```
+    !!! note
+        The `autoscaling.knative.dev/target` annotation for "Memory" specifies the integer value in Mi
 
 === "Custom metric"
 
@@ -98,6 +110,7 @@ For more information about KPA and HPA, see the documentation on [Supported Auto
           annotations:
             autoscaling.knative.dev/class: "hpa.autoscaling.knative.dev"
             autoscaling.knative.dev/metric: "<metric-name>"
+            autoscaling.knative.dev/target: "<target>"
     ```
 
     Where `<metric-name>` is your custom metric.