internal: add missing package docs

Change-Id: I1fe6930b870ee3c01fbe8af7df663b1e224f97e7
Reviewed-on: https://go-review.googlesource.com/c/pkgsite-metrics/+/465222
Auto-Submit: Julie Qiu <julieqiu@google.com>
Reviewed-by: Julie Qiu <julieqiu@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Julie Qiu <julieqiu@google.com>
diff --git a/internal/config/config.go b/internal/config/config.go
index 63aad15..37149a7 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Package config resolves shared configuration for services, and
+// provides functions to access this configuration.
 package config
 
 import (
diff --git a/internal/load/load.go b/internal/load/load.go
index 6083328..ce252fe 100644
--- a/internal/load/load.go
+++ b/internal/load/load.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Package load provides functions to load Go packages from source code.
 package load
 
 import (
diff --git a/internal/scan/parse.go b/internal/scan/parse.go
index a46dc06..be59220 100644
--- a/internal/scan/parse.go
+++ b/internal/scan/parse.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Package scan provides functionality for parsing a scan request.
 package scan
 
 import (
diff --git a/internal/worker/server.go b/internal/worker/server.go
index 980f378..dc12419 100644
--- a/internal/worker/server.go
+++ b/internal/worker/server.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// Package worker provides functionality for running a worker service.
 package worker
 
 import (