Enhance doc wrt interactions between `org-startup-folded' and `org-agenda-inhibit-startup'

* org.el (org-startup-folded):
* org.texi (Visibility cycling): Suggest to set
`org-agenda-inhibit-startup' to nil if user wants the startup
visibility settings to be honored in any circumstances.

Thanks to Tassilo for pointing this.

doc/org.texi

@@ -1297,6 +1297,7 @@ Copy the @i{visible} text in the region into the kill ring.
 @end table
 
 @vindex org-startup-folded
+@vindex org-agenda-inhibit-startup
 @cindex @code{overview}, STARTUP keyword
 @cindex @code{content}, STARTUP keyword
 @cindex @code{showall}, STARTUP keyword
@@ -1315,6 +1316,10 @@ buffer:
 #+STARTUP: showeverything
 @end example
 
+The startup visibility options are ignored when the file is open for the
+first time during the agenda generation: if you want the agenda to honor
+the startup visibility, set @code{org-agenda-inhibit-startup} to nil.
+
 @cindex property, VISIBILITY
 @noindent
 Furthermore, any entries with a @samp{VISIBILITY} property (@pxref{Properties

lisp/org.el

@@ -467,7 +467,11 @@ the following lines anywhere in the buffer:
    #+STARTUP: fold              (or `overview', this is equivalent)
    #+STARTUP: nofold            (or `showall', this is equivalent)
    #+STARTUP: content
-   #+STARTUP: showeverything"
+   #+STARTUP: showeverything
+
+By default, this option is ignored when Org opens agenda files
+for the first time.  If you want the agenda to honor the startup
+option, set `org-agenda-inhibit-startup' to nil."
   :group 'org-startup
   :type '(choice
 	  (const :tag "nofold: show all" nil)