Directory local variables: Set sentence-end-double-space to t

* .dir-locals.el: Add comments and set `sentence-end-double-space' to t.

* .dir-settings.el: Add comments and set `sentence-end-double-space' to t.

.dir-locals.el

@@ -1,4 +1,9 @@
+;; - keep in sync dir-locals.el (for Emacs >= 24) with .dir-settings.el
+;;   (for Emacs < 24)
+;; - don't use a symbolic link to prevent problems on cygwin
+;;   distributions (commit 971b9eeacd38959439ddaa7c650430cc2dcb673e)
+
 ((nil . ((indent-tabs-mode . t)
 	 (tab-width . 8)
-	 (fill-column . 70))))
-
+	 (fill-column . 70)
+	 (sentence-end-double-space . t))))

.dir-settings.el

@@ -1,4 +1,9 @@
+;; - keep in sync dir-locals.el (for Emacs >= 24) with .dir-settings.el
+;;   (for Emacs < 24)
+;; - don't use a symbolic link to prevent problems on cygwin
+;;   distributions (commit 971b9eeacd38959439ddaa7c650430cc2dcb673e)
+
 ((nil . ((indent-tabs-mode . t)
 	 (tab-width . 8)
-	 (fill-column . 70))))
-
+	 (fill-column . 70)
+	 (sentence-end-double-space . t))))