Improve documentation for tower-test

[alfiejfs]

There is currently not a lot of documentation around the tower-test library, with minimal descriptions and no usage examples. Hopefully this shouldn't be too hard to improve. I found it very difficult to use the library as I could not find too many examples online and am not yet familiar with the tower ecosystem

[an-data]

There is currently not a lot of documentation around the tower-test library, with minimal descriptions and no usage examples. Hopefully this shouldn't be too hard to improve. I found it very difficult to use the library as I could not find too many examples online and am not yet familiar with the tower ecosystem

I agree with you, It's difficult to impl some fn by tower crate, If there are many examples, it will be easy to use