Documentation/config.txt: Correct info about subsection name

Contrary to variable values, in subsection names parsing character
escape codes (besides literal escaping of " as \", and \ as \\)
is not performed; subsection name cannot contain newlines.
Signed-off-by: NJakub Narebski <jnareb@gmail.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/config.txt

@@ -37,8 +37,8 @@ in the section header, like in example below:
 
 --------
 
-Subsection names can contain any characters (doublequote '`"`', backslash
-'`\`' and newline have to be entered escaped as '`\"`', '`\\`' and '`\n`',
+Subsection names can contain any characters except newline (doublequote
+'`"`' and backslash have to be escaped as '`\"`' and '`\\`',
 respecitvely) and are case sensitive.  Section header cannot span multiple
 lines.  Variables may belong directly to a section or to a given subsection.
 You can have `[section]` if you have `[section "subsection"]`, but you