man: ClientOnionAuthDir can't be reloaded with Sandbox 1

By adding a file to the ClientOnionAuthDir and sending a HUP signal, tor would
load the new file and use it. However, that doesn't work with the Sandbox
since post initilization, nothing can be changed.

Document in the manpage that limitation within the Sandbox description.

Closes #28128

Signed-off-by: David Goulet <dgoulet@torproject.org>

changes/ticket28128

@@ -0,0 +1,4 @@
+  o Documentation (hidden service manpage, sandbox):
+    - Document in the man page that changing ClientOnionAuthDir value or
+      adding a new file in the directory will not work at runtime upon sending
+      a HUP if Sandbox 1. Closes ticket 28128.

doc/tor.1.txt

@@ -611,6 +611,7 @@ GENERAL OPTIONS
     ServerDNSResolvConfFile
     Tor must remain in client or server mode (some changes to ClientOnly and
     ORPort are not allowed).
+    ClientOnionAuthDir and any files in it won't reload on HUP signal.
     (Default: 0)
 
 [[Socks4Proxy]] **Socks4Proxy** __host__[:__port__]::