fix Polynomial.td doc filename (#88900)

Not sure how best to test this, but I think it fixes the error
https://github.com/llvm/mlir-www/actions/runs/8699908058/job/23859264085#step:7:1111

Co-authored-by: Jeremy Kun <[email protected]>
Co-authored-by: Jacques Pienaar <[email protected]>

Author: j2kun

mlir/include/mlir/Dialect/Polynomial/IR/CMakeLists.txt

@@ -1,8 +1,8 @@
 add_mlir_dialect(Polynomial polynomial)
-add_mlir_doc(PolynomialDialect PolynomialDialect Polynomial/ -gen-dialect-doc)
-add_mlir_doc(PolynomialOps PolynomialOps Polynomial/ -gen-op-doc)
-add_mlir_doc(PolynomialAttributes PolynomialAttributes Dialects/ -gen-attrdef-doc)
-add_mlir_doc(PolynomialTypes PolynomialTypes Dialects/ -gen-typedef-doc)
+add_mlir_doc(Polynomial PolynomialDialect Polynomial/ -gen-dialect-doc)
+add_mlir_doc(Polynomial PolynomialOps Polynomial/ -gen-op-doc)
+add_mlir_doc(Polynomial PolynomialAttributes Dialects/ -gen-attrdef-doc)
+add_mlir_doc(Polynomial PolynomialTypes Dialects/ -gen-typedef-doc)
 
 set(LLVM_TARGET_DEFINITIONS Polynomial.td)
 mlir_tablegen(PolynomialAttributes.cpp.inc -gen-attrdef-defs -attrdefs-dialect=polynomial)