all: cleanup usage of dashes in package documentation

Change-Id: I58453f7ed71eaca15dd3f501e4ae88d1fab19908
Reviewed-on: https://go-review.googlesource.com/12683
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>

src/debug/elf/elf.go

@@ -312,7 +312,7 @@ const (
 	SHN_HIOS      SectionIndex = 0xff3f /* Last operating system-specific. */
 	SHN_ABS       SectionIndex = 0xfff1 /* Absolute values. */
 	SHN_COMMON    SectionIndex = 0xfff2 /* Common data. */
-	SHN_XINDEX    SectionIndex = 0xffff /* Escape -- index stored elsewhere. */
+	SHN_XINDEX    SectionIndex = 0xffff /* Escape; index stored elsewhere. */
 	SHN_HIRESERVE SectionIndex = 0xffff /* Last of reserved range. */
 )
 

src/mime/multipart/writer.go

@@ -39,7 +39,8 @@ func (w *Writer) Boundary() string {
 // boundary separator with an explicit value.
 //
 // SetBoundary must be called before any parts are created, may only
-// contain certain ASCII characters, and must be 1-69 bytes long.
+// contain certain ASCII characters, and must be non-empty and
+// at most 69 bytes long.
 func (w *Writer) SetBoundary(boundary string) error {
 	if w.lastpart != nil {
 		return errors.New("mime: SetBoundary called after write")

src/net/http/request.go

@@ -340,7 +340,7 @@ func valueOrDefault(value, def string) string {
 // See https://codereview.appspot.com/7532043.
 const defaultUserAgent = "Go-http-client/1.1"
 
-// Write writes an HTTP/1.1 request -- header and body -- in wire format.
+// Write writes an HTTP/1.1 request, which is the header and body, in wire format.
 // This method consults the following fields of the request:
 //	Host
 //	URL