all: fix typo in RuneSelf, runeSelf comments

Fixes #36396

Change-Id: I52190f450fa9ac52fbf4ecdc814e954dc29029cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/213377Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/utf8.go

@@ -7,7 +7,7 @@ package runtime
 // Numbers fundamental to the encoding.
 const (
 	runeError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
-	runeSelf  = 0x80         // characters below Runeself are represented as themselves in a single byte.
+	runeSelf  = 0x80         // characters below runeSelf are represented as themselves in a single byte.
 	maxRune   = '\U0010FFFF' // Maximum valid Unicode code point.
 )
 

src/unicode/utf8/utf8.go

@@ -14,7 +14,7 @@ package utf8
 // Numbers fundamental to the encoding.
 const (
 	RuneError = '\uFFFD'     // the "error" Rune or "Unicode replacement character"
-	RuneSelf  = 0x80         // characters below Runeself are represented as themselves in a single byte.
+	RuneSelf  = 0x80         // characters below RuneSelf are represented as themselves in a single byte.
 	MaxRune   = '\U0010FFFF' // Maximum valid Unicode code point.
 	UTFMax    = 4            // maximum number of bytes of a UTF-8 encoded Unicode character.
 )