SupportBundles: Add support bundle documentation (#61855)

* add support bundle page

* Update docs/sources/troubleshooting/support-bundles/index.md

* Update docs/sources/troubleshooting/support-bundles/index.md

Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>

* copy edit

* Update docs/sources/troubleshooting/support-bundles/index.md

Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

---------

Co-authored-by: Ieva <ieva.vasiljeva@grafana.com>
Co-authored-by: Chris Moyer <chris.moyer@grafana.com>
Co-authored-by: Christopher Moyer <35463610+chri2547@users.noreply.github.com>

contribute/backend/support-bundles.md

@@ -0,0 +1,82 @@
+# Support bundles
+
+Support bundles are a way to collect all the information needed to debug a problem.
+They are generated from the support bundle menu in the UI under the Help section.
+
+The support bundle is an archive that contains one file per collector selected by
+the user.
+
+Collectors are functions in the backend that collect information about the service they are running in.
+Services can register collectors during their initialization.
+
+## Adding a new support bundle collector
+
+To add a new support bundle collector, you need to follow these steps,
+we'll use the usage stats service as an example:
+
+1. Import the support bundles registry in the service's `ProvideService` function:
+
+```go
+type UsageStats struct {
+    ...
+}
+
+func ProvideService(
+	...
+	bundleRegistry supportbundles.Service, // Bundle registry
+) (*UsageStats, error)
+```
+
+2. `make gen-go` will then be able to wire the registry to the service.
+
+3. Implement the collector
+
+```go
+func (uss *UsageStats) supportBundleCollector() supportbundles.Collector {
+	return supportbundles.Collector{
+		UID:               "usage-stats", // unique ID for the collector
+		DisplayName:       "Usage statistics", // display name for the collector in the UI
+		Description:       "Usage statistics of the Grafana instance", // description for the collector in the UI
+		IncludedByDefault: false, // whether the collector is included by default in the support bundle and can't be deselected. Most times you want this to be false.
+		Default:           false, // whether the collector is selected by default in the support bundle. User can still deselect it.
+        // Function that will actually collect the file during the support bundle generation.
+		Fn: func(ctx context.Context) (*supportbundles.SupportItem, error) {
+            // Add your service's logic to collect the information you need
+            // In this example we are collecting the usage stats and marshalling them to JSON
+            // This helps us get information about the usage of the Grafana instance
+			report, err := uss.GetUsageReport(context.Background())
+			if err != nil {
+				return nil, err
+			}
+
+			data, err := json.Marshal(report)
+			if err != nil {
+				return nil, err
+			}
+
+			return &supportbundles.SupportItem{
+                // filename of the file in the archive
+                // can be any extension. (most common is .json and .md)
+				Filename:  "usage-stats.json",
+				FileBytes: data, // []byte of the file
+			}, nil
+		},
+	}
+}
+```
+
+4. Register the collector in the service's `ProvideService` function:
+
+```go
+func ProvideService(
+    ...
+) (*UsageStats, error) {
+	s := &UsageStats{
+        //	...
+	}
+
+	bundleRegistry.RegisterSupportItemCollector(s.supportBundleCollector())
+
+	return s, nil
+}
+```