[css-table] Added slot definition

Author: gregwhitworth

css-tables-3/Overview.bs

@@ -228,6 +228,11 @@ spec:css21; type:property; text:max-width
 					A sequence of sibling boxes is consecutive
 						if each box in the sequence is consecutive to the one before it in the sequence.
 				</dl>
+				
+				<dt><dfn id="table-slot">slot</dfn>
+				<dd>
+					The <a>slot</a> is an available space created by the intersection of and inline and block
+					<a>table-track</a>.
 
 	<!--------------------------------------------------------------------------------->
 	<h3 id="fixup">Fixup</h3>
@@ -649,9 +654,9 @@ spec:css21; type:property; text:max-width
 				<li><b>Determine the amount of rows/columns the table requires.</b><br/>
 					This is done by executing the steps described in [[#dimensioning-the-row-column-grid]].
 
-				<li><b>&lbrack;A&rbrack; If the row/column grid has at least one slot:</b>
+				<li><b>&lbrack;A&rbrack; If the row/column grid has at least one <a>slot</a>:</b>
 					<ol>
-						<li><b>Ensure each cell slot is occupied by at least one cell.</b><br/>
+						<li><b>Ensure each cell <a>slot</a> is occupied by at least one cell.</b><br/>
 							This is done by executing the steps described in [[#missing-cells-fixup]].
 
 						<li><b>Compute the minimun width of each row/column.</b><br/>