[doc] usage: Actually add non-breaking spaces to config file

In 3625207 I attempted to add
non-breaking spaces to a filepath so it would stay on one line.
Before this I had accidentally deleted my work but found it saved
in my sphinx build cache, so I copied my changes from that cache.

Unfortunately the cached version replaced non-breaking spaces with
real spaces and 3625207 was made
reverted.

This commit re-adds the non-breaking spaces.

doc/usage.rst

@@ -352,7 +352,7 @@ line arguments, it is more convenient to create a ``looking-glass-host.ini``
 config file for persistent configuration changes.
 
 This file must be placed in the same directory as the Looking Glass host, by
-default ``C:\Program Files\Looking Glass (host)\``.
+default ``C:\Program Files\Looking Glass (host)\``.
 
 .. _host_capture: