feat(develop): Add page context (#13203)

This adds a new context to develop docs:

The new `page` context should be used to add information about the
current page that an event originated on. It should be used for
web-based client SDKs instead of putting this information into
`event.request`.

Relay will need to extract data from this (if available) instead of
`event.request`.

Author: mydea

develop-docs/sdk/data-model/event-payloads/contexts.mdx

@@ -748,6 +748,49 @@ envelope endpoint.
 }
 ```
 
+## Page Context
+
+Page context contains information about the page that the event occurred on.
+
+`url`
+
+: **Required.** The URL of the page that the event occurred on, excluding query parameters & fragment.
+
+- Example: `https://sentry.io/issues`
+
+`http.query`
+
+: **Optional.** The query parameters of the page that the event occurred on.
+
+- Example: `?page=1`
+
+`http.fragment`
+
+: **Optional.** The fragment of the page that the event occurred on.
+
+- Example: `#123`
+
+`referer`
+
+: _Optional_. The referer of the page that the event occurred on.
+
+- Example: `https://sentry.io/`
+
+**Example Page Context**
+
+```json
+{
+  "contexts": {
+    "page": {
+      "url": "https://sentry.io/issues",
+      "http.query": "?page=1",
+      "http.fragment": "#123",
+      "referer": "https://sentry.io/"
+    }
+  }
+}
+```
+
 ## Response Context
 
 Response context contains information about the HTTP response associated with the event.
@@ -799,7 +842,7 @@ The required field is `package` which should contain the package or framework wh
   "contexts": {
     "missing_instrumentation": {
       "package": "express",
-      "javascript.is_cjs": true,
+      "javascript.is_cjs": true
     }
   }
 }

develop-docs/sdk/data-model/event-payloads/request.mdx

@@ -4,9 +4,8 @@ sidebar_order: 8
 ---
 
 The Request interface contains information on a HTTP request related to the
-event. In client SDKs, this can be an outgoing request, or the request that
-rendered the current web page. On server SDKs, this could be the incoming web
-request that is being handled.
+event. In client SDKs, this can be an outgoing request (use the [page context](../contexts/#page-context) to track the page that the request was made from).
+On server SDKs, this could be the incoming web request that is being handled.
 
 The data variable should only contain the request body (not the query string).
 It can either be a dictionary (for standard HTTP requests) or a raw request