all: spell "Deprecated: Use etc" consistently

Change-Id: I209b75dc8dc4da881b68e5c5d98cbf08c1032dfc
Reviewed-on: https://go-review.googlesource.com/c/go/+/171098Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

src/crypto/x509/x509.go

@@ -2278,7 +2278,7 @@ type CertificateRequest struct {
 	// Attributes contains the CSR attributes that can parse as
 	// pkix.AttributeTypeAndValueSET.
 	//
-	// Deprecated: use Extensions and ExtraExtensions instead for parsing and
+	// Deprecated: Use Extensions and ExtraExtensions instead for parsing and
 	// generating the requestedExtensions attribute.
 	Attributes []pkix.AttributeTypeAndValueSET
 

src/go/importer/importer.go

@@ -73,7 +73,7 @@ func ForCompiler(fset *token.FileSet, compiler string, lookup Lookup) types.Impo
 
 // For calls ForCompiler with a new FileSet.
 //
-// Deprecated: use ForCompiler, which populates a FileSet
+// Deprecated: Use ForCompiler, which populates a FileSet
 // with the positions of objects created by the importer.
 func For(compiler string, lookup Lookup) types.Importer {
 	return ForCompiler(token.NewFileSet(), compiler, lookup)

src/runtime/cpuprof.go

@@ -179,7 +179,7 @@ func (p *cpuProfile) addLostAtomic64(count uint64) {
 // The details of generating that format have changed,
 // so this functionality has been removed.
 //
-// Deprecated: use the runtime/pprof package,
+// Deprecated: Use the runtime/pprof package,
 // or the handlers in the net/http/pprof package,
 // or the testing package's -test.cpuprofile flag instead.
 func CPUProfile() []byte {