docs: square odds example in rxjs guide (#24947)

Added argument type to filter function of rxjs. Fixed the
return value of filtering of odd numbers

PR Close #24947

aio/content/examples/rx-library/src/operators.1.ts

@@ -8,7 +8,7 @@ const nums = of(1, 2, 3, 4, 5);
 
 // Create a function that accepts an Observable.
 const squareOddVals = pipe(
-  filter(n => n % 2),
+  filter((n: number) => n % 2 !== 0),
   map(n => n * n)
 );