fix whitespace in rootrc.in

Author: jblomer

config/rootrc.in

@@ -242,7 +242,7 @@ GeomPainter.Name:            @root_geompainter_type@
 # THttpServer specific settings
 # location of JavaScript ROOT sources
 #HttpServ.JSRootPath:        @jsrootdir@
-# Default setting for enabling or disabling JSROOT. 
+# Default setting for enabling or disabling JSROOT.
 # This can be toggled in the notebook using the `%jsroot on/off` command.
 Jupyter.JSRoot:               on