fix: symbol shadows table has a single column

Author: alandefreitas

share/mrdocs/addons/generator/adoc/partials/symbol.adoc.hbs

@@ -134,7 +134,7 @@
 {{! Using symbols }}
 {{#if symbol.shadows}}
 {{#> markup/dynamic-level-h }}Introduced Symbols{{/markup/dynamic-level-h}}
-[cols=2]
+[cols=1]
 |===
 | Name
 {{#each symbol.shadows}}