Update the network profiling documentation (#10072)

Author: mrproliu

docs/en/changes/changes.md

@@ -205,5 +205,6 @@
 * Add new docs for `Record` query protocol
 * Update `Server Agents` and `Compatibility` for PHP agent.
 * Add docs for profiling.
+* Update the network profiling documentation.
 
 All issues and pull requests are [here](https://github.com/apache/skywalking/milestone/149?closed=1)

docs/en/setup/backend/backend-k8s-network-monitoring.md

@@ -16,6 +16,19 @@ agent-analyzer:
     meterAnalyzerActiveFiles: ${SW_METER_ANALYZER_ACTIVE_FILES:network-profiling}
 ```
 
+## Sampling config
+
+**Notice the precondition, the HTTP request must have the trace header in SkyWalking(`sw8` header) or Zipkin(`b3` header(s)) format.**
+
+The sampling configurations define the sampling boundaries for the HTTP traffic. When a HTTP calling is sampled,
+the SkyWalking Rover could collect the HTTP request/response raw data and upload it to the span attached event. 
+
+The sampling config contains multiple rules, and each of rules has the following configurations:
+1. `URI Regex`: The match pattern for HTTP requests is HTTP URI-oriented. Match all requests if the URI regex is not set.
+2. `Minimal Request Duration (ms)`: Sample the HTTP requests with slower latency than this threshold.
+3. `Sample HTTP requests and responses with tracing when the response code is between 400 and 499`: This is OFF by default.
+4. `Sample HTTP requests and responses with tracing when the response code is between 500 and 599`: This is ON by default.
+
 ## Supported metrics
 
 After SkyWalking OAP server receives the metrics from the SkyWalking Rover, it supports to analysis the following data:
@@ -33,3 +46,14 @@ After SkyWalking OAP server receives the metrics from the SkyWalking Rover, it s
 3. Local process communicate with peer address exception data, including following types:
    1. **Retransmit**: The count of TCP package is retransmitted.
    2. **Drop**: The count of TCP package is dropped.
+4. HTTP/1.x request/response related metrics, including following types:
+   1. **Request CPM**: The calls per minute of requests.
+   2. **Response CPM**: The calls per minute of responses with status code.
+   3. **Request Package Size**: The size(KB) of the request package.
+   4. **Response Package Size**: The size(KB) of the response package.
+   5. **Client Side Response Duration**: The duration(ms) of the client receive the response.
+   6. **Server Side Response Duration**: The duration(ms) of the server send the response.
+5. HTTP sampled request with traces, including following types:
+   1. **Slow traces**: The traces which have slow duration.
+   2. **Traces from HTTP Code in [400, 500) (ms)**: The traces which response status code in [400, 500).
+   3. **Traces from HTTP Code in [500, 600) (ms)**: The traces which response status code in [500, 600).

docs/en/ui/README.md

@@ -55,6 +55,7 @@ To display one or more metrics in a graph, the following information is required
 |read all values of labels in the duration|Table|<img src="https://skywalking.apache.org/screenshots/9.2.0/customize-dashboard-metrics-20220817-tables.png" />|
 |read all values in the duration|Area|<img src="https://skywalking.apache.org/screenshots/9.2.0/customize-dashboard-metrics-20220817-area.png" />|
 |read all values in the duration|Service/Instance/Endpoint List|<img src="https://skywalking.apache.org/screenshots/9.2.0/customize-dashboard-metrics-20220817-entity-table.png" />|
+|read sampled records in the duration|Records List|<img src="https://skywalking.apache.org/screenshots/9.2.0/customized-dashboard-metrics-20221201-sampled-records.png" />|
 
 #### Calculations