refine comments for package core (#5014)

* Refine Comments

* refine comments for cache.go

* refine comments for log.go

* Update orm.go

* refine comments for orm_log.go,types.go

* Update utils.go

* Update doc.go

* refine comments

* refine comments

* Update db.go

* refine comments for core

core/bean/doc.go

@@ -12,6 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// bean is a basic package
+// Package bean is a basic package
 // it should not depend on other modules except common module, log module and config module
 package bean