cmd/guru: fix several functions godoc comment prefix

The several functions not exported, Use "The xxx function ..." rule.

Change-Id: Iaba2490b4a9675213f70d055bd9ded9e5a245aa5
Reviewed-on: https://go-review.googlesource.com/c/47872
Reviewed-by: Alan Donovan <adonovan@google.com>

cmd/guru/callees.go

@@ -18,7 +18,7 @@ import (
 	"golang.org/x/tools/go/ssa/ssautil"
 )
 
-// Callees reports the possible callees of the function call site
+// The callees function reports the possible callees of the function call site
 // identified by the specified source location.
 func callees(q *Query) error {
 	lconf := loader.Config{Build: q.Build}

cmd/guru/callers.go

@@ -16,7 +16,7 @@ import (
 	"golang.org/x/tools/go/ssa/ssautil"
 )
 
-// Callers reports the possible callers of the function
+// The callers function reports the possible callers of the function
 // immediately enclosing the specified source location.
 //
 func callers(q *Query) error {

cmd/guru/callstack.go

@@ -16,7 +16,7 @@ import (
 	"golang.org/x/tools/go/ssa/ssautil"
 )
 
-// Callstack displays an arbitrary path from a root of the callgraph
+// The callstack function displays an arbitrary path from a root of the callgraph
 // to the function at the current position.
 //
 // The information may be misleading in a context-insensitive

cmd/guru/implements.go

@@ -19,7 +19,7 @@ import (
 	"golang.org/x/tools/refactor/importgraph"
 )
 
-// Implements displays the "implements" relation as it pertains to the
+// The implements function displays the "implements" relation as it pertains to the
 // selected type.
 // If the selection is a method, 'implements' displays
 // the corresponding methods of the types that would have been reported

cmd/guru/referrers.go

@@ -27,7 +27,7 @@ import (
 	"golang.org/x/tools/refactor/importgraph"
 )
 
-// Referrers reports all identifiers that resolve to the same object
+// The referrers function reports all identifiers that resolve to the same object
 // as the queried identifier, within any package in the workspace.
 func referrers(q *Query) error {
 	fset := token.NewFileSet()