Fix docs table for selector syntax

src/ifcopenshell-python/docs/ifcopenshell-python/selector_syntax.rst

@@ -254,7 +254,7 @@ nest formulas, for example ``concat(title("foo"), lower("Bar"))`` will produce
     "``imperial_length({{value}}, {{precision}}, {{input_unit}}, {{output_unit}}, {{suppress_zero_inches}})``", "``imperial_length(3.0, 4, ""foot"", ""foot"", true)`` OR ``imperial_length(3.0, 4, ""foot"", ""foot"", false)``", "``3'`` OR ``3' - 0""``", "The ``{{value}}`` may be specified either as ``foot`` or ``inch`` depending on ``{{input_unit}}``. The ``{{value}}`` is then rounded to the nearest ``1/{{precision}}`` inch, then formatted using fractional feet and inches if ``{{output_unit}}`` is set to ``foot``, or just inches if ``{{output_unit}}`` is set to ``inch``. When ``{{suppress_zero_inches}}`` is ``true`` (default), measurements with zero inches will omit the inch portion (e.g., ``3'`` instead of ``3' - 0""``)."
     "``sort({{values}})``", "``sort({{mats.Name}})``", "``Name1, Name2``", "Sorts a list of items."
     "``reverse({{values}})``", "``reverse({{mats.Name}})``", "``Name2, Name1``", "Reverses a list of items."
-    "``join({{separator}}, {{values}})``", "``join("-", {{mats.Name}})``", "``Name1-Name2``", "Joins a list of items with a custom separator. By default, all lists a rendered as comma separated."
+    "``join({{separator}}, {{values}})``", "``join(""-"", {{mats.Name}})``", "``Name1-Name2``", "Joins a list of items with a custom separator. By default, all lists a rendered as comma separated."
     "``{{value1}}[+-*/]{{value2}}``", "``{{z}}+3``", "``5``", "Does arithmetic. Typical operators such as +, -, \*, and / are allowed and can be mixed with other variables and formatting functions."
 
 When using queries in an IfcAnnotation tag surround with backticks.