Gofmt and goimports config.go, add documentation

Signed-off-by: Nikhil Pandeti <nikhil.pandeti@utexas.edu>

cmd/buildkitd/config/config.go

@@ -77,7 +77,7 @@ type OCIConfig struct {
 	// incomplete and the intention is to make it default without config.
 	UserRemapUnsupported string `toml:"userRemapUnsupported"`
 	// For use in storing the OCI worker binary name that will replace buildkit-runc
-	Binary        	 string            `toml:"binary"`
+	Binary string `toml:"binary"`
 }
 
 type ContainerdConfig struct {

docs/buildkitd.toml.md

@@ -46,6 +46,7 @@ insecure-entitlements = [ "network.host", "security.insecure" ]
   noProcessSandbox = false
   gc = true
   gckeepstorage = 9000
+  binary = "" # OCI worker binary name, default binary is buildkit-runc
   [worker.oci.labels]
     "foo" = "bar"