Tiny texinfo markup fixes

* doc/lispref/edebug.texi (Edebug Views):
* doc/lispref/loading.texi (Library Search):
* doc/lispref/os.texi (User Identification): Markup fixes.

doc/lispref/edebug.texi

@@ -663,7 +663,7 @@ definition in the future.
 Toggle whether Edebug saves and restores the outside window
 configuration (@code{edebug-toggle-save-windows}).
 
-With a prefix argument, @code{W} only toggles saving and restoring of
+With a prefix argument, @kbd{W} only toggles saving and restoring of
 the selected window.  To specify a window that is not displaying the
 source code buffer, you must use @kbd{C-x X W} from the global keymap.
 @end table

doc/lispref/files.texi

@@ -3338,6 +3338,7 @@ each have handlers.
 file---such as the ones that implement completion of host names for
 remote file names---should have a non-@code{nil} @code{safe-magic}
 property.  For instance, Emacs normally protects directory names
+@c FIXME I don't think this means the PATH environment variable?
 it finds in @code{PATH} from becoming magic, if they look like magic
 file names, by prefixing them with @samp{/:}.  But if the handler that
 would be used for them has a non-@code{nil} @code{safe-magic}

doc/lispref/loading.texi

@@ -338,7 +338,7 @@ If the environment variable @env{EMACSLOADPATH} is set, it modifies
 the above initialization procedure.  Emacs initializes
 @code{load-path} based on the value of the environment variable.
 
-The syntax of @env{EMACSLOADPATH} is the same as used for @code{PATH};
+The syntax of @env{EMACSLOADPATH} is the same as used for @env{PATH};
 directories are separated by @samp{:} (or @samp{;}, on some
 operating systems).
 @ignore

doc/lispref/os.texi

@@ -1194,7 +1194,7 @@ This function returns the full name of the logged-in user---or the value
 of the environment variable @env{NAME}, if that is set.
 
 If the Emacs process's user-id does not correspond to any known user (and
-provided @code{NAME} is not set), the result is @code{"unknown"}.
+provided @env{NAME} is not set), the result is @code{"unknown"}.
 
 If @var{uid} is non-@code{nil}, then it should be a number (a user-id)
 or a string (a login name).  Then @code{user-full-name} returns the full