Correct spec anchors

It seems somewhere along the way an additional underscore was added to the anchors in the spec, breaking these links.

Author: andrewpollock

internal/typesinternal/errorcode.go

@@ -838,7 +838,7 @@ const (
 	// InvalidCap occurs when an argument to the cap built-in function is not of
 	// supported type.
 	//
-	// See https://golang.org/ref/spec#Lengthand_capacity for information on
+	// See https://golang.org/ref/spec#Length_and_capacity for information on
 	// which underlying types are supported as arguments to cap and len.
 	//
 	// Example:
@@ -859,7 +859,7 @@ const (
 	// InvalidCopy occurs when the arguments are not of slice type or do not
 	// have compatible type.
 	//
-	// See https://golang.org/ref/spec#Appendingand_copying_slices for more
+	// See https://golang.org/ref/spec#Appending_and_copying_slices for more
 	// information on the type requirements for the copy built-in.
 	//
 	// Example:
@@ -897,7 +897,7 @@ const (
 	// InvalidLen occurs when an argument to the len built-in function is not of
 	// supported type.
 	//
-	// See https://golang.org/ref/spec#Lengthand_capacity for information on
+	// See https://golang.org/ref/spec#Length_and_capacity for information on
 	// which underlying types are supported as arguments to cap and len.
 	//
 	// Example:
@@ -914,7 +914,7 @@ const (
 
 	// InvalidMake occurs when make is called with an unsupported type argument.
 	//
-	// See https://golang.org/ref/spec#Makingslices_maps_and_channels for
+	// See https://golang.org/ref/spec#Making_slices_maps_and_channels for
 	// information on the types that may be created using make.
 	//
 	// Example: