Fix missing ]

lib/galaxy/tools/xsd/galaxy.xsd

@@ -3903,7 +3903,7 @@ as Python variables and are thus referred to without the $ used for the Cheetah
 template (used in the ``<command>`` tag). Variables that are part of
 conditionals are accessed using a dictionary named after the conditional. Boolean
 parameters appear as booleans, not the value of their ``truevalue`` and
-``falsevalue`` attributes. In the example below, ``options["selection_mode"`` would
+``falsevalue`` attributes. In the example below, ``options["selection_mode"]`` would
 appear as ``$options.selection_mode`` in Cheetah. Similarly ``options["vcf_output"]``
 would appear as ``$options.vcf_output`` having the values ``'--vcf'`` when true and
 ``''`` when false in Cheetah.