Add examples to the Combinators page

### Description

**location:** 'docs\src\pages\docs\functions\combinators.md'

Most `Combinators` are missing their examples. We need to get them added to help with new people coming on to the library

### Task List

* [x] `applyTo`
* [x] `composeB`
* [x] `constant`
* [x] `flip`
* [ ] `identity`
* [x] `substitution`

For more information, see the [`CONTRIBUTING`][contributing] guide.

### Further Information

This was sourced from https://github.com/evilsoft/crocks/issues/42

[contributing]: https://github.com/evilsoft/crocks/blob/master/CONTRIBUTORS.md