docs: add shp buildrun gather command documentation

Signed-off-by: karthik balasubramanian <karthikbalasubramanian08@gmail.com>

Author: kaizakin

docs/shp_buildrun.md

@@ -26,6 +26,7 @@ shp buildrun [flags]
 * [shp buildrun cancel](shp_buildrun_cancel.md)	 - Cancel BuildRun
 * [shp buildrun create](shp_buildrun_create.md)	 - Creates a BuildRun instance.
 * [shp buildrun delete](shp_buildrun_delete.md)	 - Delete BuildRun
+* [shp buildrun gather](shp_buildrun_gather.md)	 - Gather BuildRun diagnostics into a single directory or archive.
 * [shp buildrun list](shp_buildrun_list.md)	 - List Builds
 * [shp buildrun logs](shp_buildrun_logs.md)	 - See BuildRun log output
 

docs/shp_buildrun_gather.md

@@ -0,0 +1,44 @@
+## shp buildrun gather
+
+Gather BuildRun diagnostics into a single directory or archive.
+
+### Synopsis
+
+
+Gather collects the BuildRun object, the TaskRun created for it, the Pod created
+for that TaskRun, and all the container logs into a single directory.
+
+By default the command writes:
+
+  buildrun.yaml
+  taskrun.yaml
+  pod.yaml
+  logs/*.log
+
+Use --archive to package the gathered files as a .tar.gz archive.
+
+
+```
+shp buildrun gather <name> [flags]
+```
+
+### Options
+
+```
+  -z, --archive         package gathered diagnostics as a .tar.gz archive
+  -h, --help            help for gather
+  -o, --output string   directory to write gathered files (default ".")
+```
+
+### Options inherited from parent commands
+
+```
+      --kubeconfig string        Path to the kubeconfig file to use for CLI requests.
+  -n, --namespace string         If present, the namespace scope for this CLI request
+      --request-timeout string   The length of time to wait before giving up on a single server request. Non-zero values should contain a corresponding time unit (e.g. 1s, 2m, 3h). A value of zero means don't timeout requests. (default "0")
+```
+
+### SEE ALSO
+
+* [shp buildrun](shp_buildrun.md)	 - Manage BuildRuns
+