spec: use consistent capitalization for rune literal hex constants

Fixes #47368

Change-Id: I2f65c0008658532123f04d08e99e5d083f33461a
Reviewed-on: https://go-review.googlesource.com/c/go/+/337234
Trust: Ian Lance Taylor <[email protected]>
Trust: Robert Griesemer <[email protected]>
Reviewed-by: Emmanuel Odeke <[email protected]>
Reviewed-by: Robert Griesemer <[email protected]>

Author: ianlancetaylor

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of Jul 1, 2021",
+	"Subtitle": "Version of Jul 24, 2021",
 	"Path": "/ref/spec"
 }-->
 
@@ -490,8 +490,8 @@ <h3 id="Rune_literals">Rune literals</h3>
 \n   U+000A line feed or newline
 \r   U+000D carriage return
 \t   U+0009 horizontal tab
-\v   U+000b vertical tab
-\\   U+005c backslash
+\v   U+000B vertical tab
+\\   U+005C backslash
 \'   U+0027 single quote  (valid escape only within rune literals)
 \"   U+0022 double quote  (valid escape only within string literals)
 </pre>