Fix benchmark build errors (#82)

The benchmark project itself builds just fine. However, when you attempt
to run the benchmarks, the BenchmarkDotNet generated code fails to
adhere to my `.editorconfig` settings and then it throws errors. After
more time than I care to admit fighting with it, I have landed on
disabling the offending rule for `*.notcs` files.

```
[*.notcs] # BenchmarkDotNet generated files

# CS1591: Missing XML comment for publicly visible type or member
dotnet_diagnostic.CS1591.severity = none
```

.editorconfig

@@ -229,3 +229,8 @@ csharp_style_unused_value_expression_statement_preference = discard_variable
 
 # IDE0059: Remove unnecessary value assignment
 csharp_style_unused_value_assignment_preference = discard_variable
+
+[*.notcs] # BenchmarkDotNet generated files
+
+# CS1591: Missing XML comment for publicly visible type or member
+dotnet_diagnostic.CS1591.severity = none