lisp/*.el, src/*.c: Doc fixes related to returning t vs non-nil

* lisp/progmodes/flymake-proc.el (flymake-proc--find-buffer-for-file):
Doc fix; return value is a buffer, not t.

* lisp/progmodes/ebrowse.el (ebrowse-member-display-p):
Doc fix; return value is the MEMBER argument, not nil.

* lisp/files.el (hack-one-local-variable-eval-safep):
* lisp/play/doctor.el (doctor-nounp, doctor-pronounp):
* lisp/progmodes/flymake-proc.el (flymake-proc--check-include):
* lisp/progmodes/js.el (js--broken-arrow-terminates-line-p):
Doc fix; a non-nil return value is not always t.

* lisp/image.el (image-type-available-p):
* lisp/simple.el (region-active-p):
* lisp/window.el (frame-root-window-p):
* src/buffer.c (Fbuffer_live_p):
* src/image.c (Finit_image_library):
* src/window.c (Fwindow_minibuffer_p):
Doc fix; a non-nil return value is always t.

* doc/lispref/minibuf.texi (Minibuffer Windows): Doc fix.

src/buffer.c

@@ -383,7 +383,7 @@ nsberror (Lisp_Object spec)
 }
 
 DEFUN ("buffer-live-p", Fbuffer_live_p, Sbuffer_live_p, 1, 1, 0,
-       doc: /* Return non-nil if OBJECT is a buffer which has not been killed.
+       doc: /* Return t if OBJECT is a buffer which has not been killed.
 Value is nil if OBJECT is not a buffer or if it has been killed.  */)
   (Lisp_Object object)
 {

src/image.c

@@ -10053,7 +10053,7 @@ The list of capabilities can include one or more of the following:
 
 DEFUN ("init-image-library", Finit_image_library, Sinit_image_library, 1, 1, 0,
        doc: /* Initialize image library implementing image type TYPE.
-Return non-nil if TYPE is a supported image type.
+Return t if TYPE is a supported image type.
 
 If image libraries are loaded dynamically (currently only the case on
 MS-Windows), load the library for TYPE if it is not yet loaded, using

src/window.c

@@ -384,7 +384,7 @@ If FRAME is omitted or nil, it defaults to the selected frame.  */)
 
 DEFUN ("window-minibuffer-p", Fwindow_minibuffer_p,
        Swindow_minibuffer_p, 0, 1, 0,
-       doc: /* Return non-nil if WINDOW is a minibuffer window.
+       doc: /* Return t if WINDOW is a minibuffer window.
 WINDOW must be a valid window and defaults to the selected one.  */)
   (Lisp_Object window)
 {