mention cetz issue link

Author: PgBiel

README.md

@@ -638,7 +638,7 @@ I have begun [work on bringing many tablex improvements to built-in Typst tables
 
 - Allow gradients and patterns in fills (https://github.com/PgBiel/typst-tablex/pull/87)
 - Fixed a critical bug where `line` in tablex cells would misbehave (https://github.com/PgBiel/typst-tablex/issues/80)
-  - CeTZ and drawing in general should now work properly within tablex cells.
+  - CeTZ and drawing in general should now work properly within tablex cells (see https://github.com/johannes-wolf/cetz/issues/345).
   - Also fixes a problem with nested tables (https://github.com/PgBiel/typst-tablex/issues/34)
 - Fixed negative line expansion within a single cell (https://github.com/PgBiel/typst-tablex/pull/84)
   - Negative line expansion across multiple cells isn't yet supported.