Tweak 13913 fix: clarify that the behavior is not promised

Also, it's->its.  The apostrophe is used if and only if it's a
contraction for "it is".

changes/bug13913

@@ -1,5 +1,7 @@
   o Documentation:
     - Clarify HiddenServiceDir option description in manpage to make it
-      clear that directory in question is relative to current working 
-      directory of Tor instance if it is defined as a relative path. Fixes
+      clear that relative paths are taken with respect to the current
+      working
+      directory of Tor instance. Also clarify that this behavior is
+      not guaranteed to remain indefinitely. Fixes
       issue 13913.

doc/tor.1.txt

@@ -2032,8 +2032,11 @@ The following options are used to configure a hidden service.
     Store data files for a hidden service in DIRECTORY. Every hidden service
     must have a separate directory. You may use this option  multiple times to
     specify multiple services. DIRECTORY must be an existing directory.
-    NB: if DIRECTORY is defined in relative way, it will be relative to current
-    working directory of Tor instance, not it's DataDirectory.
+    (Note: in current versions of Tor, if DIRECTORY is a relative path,
+    it will be relative to current
+    working directory of Tor instance, not to its DataDirectory.  Do not
+    rely on this behavior; it is not guaranteed to remain the same in future
+    versions.)
 
 [[HiddenServicePort]] **HiddenServicePort** __VIRTPORT__ [__TARGET__]::
     Configure a virtual port VIRTPORT for a hidden service. You may use this