Fix page size in function list (#97)

`slice()` doesn't include the end element in the array that returns, so
we were rendering 9 functions instead of 10.

src/web/rules/RuleHelper.jsx

@@ -111,7 +111,7 @@ end`,
       return <Spinner />;
     }
 
-    const pagedEntries = this.state.functionDescriptors.slice((this.state.currentPage - 1) * this.state.pageSize, (this.state.currentPage * this.state.pageSize) - 1);
+    const pagedEntries = this.state.functionDescriptors.slice((this.state.currentPage - 1) * this.state.pageSize, this.state.currentPage * this.state.pageSize);
 
     return (
       <Panel header="Rules quick reference">