sh: Document the expansion changes in the man page.

Note that the following sentence
> Enclosing the full parameter expansion string in double-quotes does not
> cause the following four varieties of pattern characters to be quoted,
> whereas quoting characters within the braces has this effect.
is now true, but used to be incorrect.

bin/sh/sh.1

@@ -32,7 +32,7 @@
 .\"	from: @(#)sh.1	8.6 (Berkeley) 5/4/95
 .\" $FreeBSD$
 .\"
-.Dd March 6, 2010
+.Dd April 4, 2010
 .Dt SH 1
 .Os
 .Sh NAME
@@ -1178,10 +1178,20 @@ consists of all characters until the matching
 .Ql } .
 Any
 .Ql }
-escaped by a backslash or within a quoted string, and characters in
+escaped by a backslash or within a single-quoted string, and characters in
 embedded arithmetic expansions, command substitutions, and variable
 expansions, are not examined in determining the matching
 .Ql } .
+Except for the variants with
+.Ql + ,
+.Ql - ,
+.Ql =
+or
+.Ql ?\& ,
+any
+.Ql }
+within a double-quoted string is also not examined in determining the matching
+.Ql } .
 .Pp
 The simplest form for parameter expansion is:
 .Pp
@@ -1265,6 +1275,14 @@ is substituted.
 In the parameter expansions shown previously, use of the colon in the
 format results in a test for a parameter that is unset or null; omission
 of the colon results in a test for a parameter that is only unset.
+.Pp
+The
+.Ar word
+inherits the type of quoting
+(unquoted, double-quoted or here-document)
+from the surroundings,
+with the exception that a backslash that quotes a closing brace is removed
+during quote removal.
 .Bl -tag -width indent
 .It Li ${# Ns Ar parameter Ns Li }
 String Length.