doc: add documentation overview for grpc, file and datasource packages

pkg/gofr/datasource/datasource.go

@@ -1,3 +1,8 @@
+/*
+Package datasource provides an interface for registering datasources with the gofr framework.
+A datasource is a componentc that provides access to data, such as a database or a message queue.
+The Datasource interface defines a method for registering a datasource with the gofr framework.
+*/
 package datasource
 
 import "gofr.dev/pkg/gofr/config"

pkg/gofr/file/file.go

@@ -1,3 +1,4 @@
+// Package file provides a simple representation of a file and its metadata.
 package file
 
 type file struct {

pkg/gofr/grpc/log.go

@@ -1,3 +1,4 @@
+// Package grpc provides functionality for creating and running gRPC servers within the GoFr framework.
 package grpc
 
 import (