Fixed typos in examples

[burhanharoon]

The word "Customized" was mistyped to "Cutomized" in the following files:

• https://github.com/greyli/bootstrap-flask/blame/master/examples/bootstrap4/templates/table.html#L9
• https://github.com/greyli/bootstrap-flask/blame/master/examples/bootstrap5/templates/table.html#L9

I fixed the spelling.

Fixes #206

[greyli]

Thanks!