Update the manual wrt comments.

* org.texi (Comment lines): Update wrt comments.

* orgguide.texi (Comment lines): Update wrt comments.

doc/org.texi

@@ -9148,11 +9148,11 @@ a horizontal line (@samp{<hr/>} in HTML and @code{\hrule} in @LaTeX{}).
 @cindex exporting, not
 @cindex #+BEGIN_COMMENT
 
-Lines starting with @samp{#} in column zero are treated as comments and will
-never be exported.  If you want an indented line to be treated as a comment,
-start it with @samp{#+ }.  Also entire subtrees starting with the word
-@samp{COMMENT} will never be exported.  Finally, regions surrounded by
-@samp{#+BEGIN_COMMENT} ... @samp{#+END_COMMENT} will not be exported.
+Lines starting with zero or more whitespace characters followed by @samp{#}
+are treated as comments and will never be exported.  Also entire subtrees
+starting with the word @samp{COMMENT} will never be exported.  Finally,
+regions surrounded by @samp{#+BEGIN_COMMENT} ... @samp{#+END_COMMENT} will
+not be exported.
 
 @table @kbd
 @kindex C-c ;

doc/orgguide.texi

@@ -2160,11 +2160,11 @@ consisting of only dashes, and at least 5 of them.
 @node Comment lines,  , Emphasis and monospace, Structural markup elements
 @subheading Comment lines
 
-Lines starting with @samp{#} in column zero are treated as comments and will
-never be exported.  If you want an indented line to be treated as a comment,
-start it with @samp{#+ }.  Also entire subtrees starting with the word
-@samp{COMMENT} will never be exported.  Finally, regions surrounded by
-@samp{#+BEGIN_COMMENT} ... @samp{#+END_COMMENT} will not be exported.
+Lines starting with zero or more whitespace characters followed by @samp{#}
+are treated as comments and will never be exported.  Also entire subtrees
+starting with the word @samp{COMMENT} will never be exported.  Finally,
+regions surrounded by @samp{#+BEGIN_COMMENT} ... @samp{#+END_COMMENT} will
+not be exported.
 
 @table @kbd
 @item C-c ;