Suggested Documentation Changes to "Tutorial: Basic Logic"

[doc link](https://google.github.io/xls/tutorials/float_to_int/)

* Bootstrapping
* In paragraph 2 "Function parameter declarations!" here are a few dashes that look like they are badly formatted and might be better off as list sub-items. Instead of:
`- u1, u8, and u23 are all shortcuts for the type uN[1], uN[8], and uN[23]. The uN[X] construct declares an X-bit wide unsigned type. There is also sN[X], which declares an X-bit wide signed type. - Other type shortcuts exist such as bitsX, bool (alias for uN[1]), and u[1-64] and s[1-64], being aliases for uN[1] through uN[64] and sN[1] through sN[64].`
How about
* `u1, u8, and u23 are all shortcuts for the type uN[1], uN[8], and uN[23]. The uN[X] construct declares an X-bit wide unsigned type. There is also sN[X], which declares an X-bit wide signed type.`
* `Other type shortcuts exist such as bitsX, bool (alias for uN[1]), and u[1-64] and s[1-64], being aliases for uN[1] through uN[64] and sN[1] through sN[64].`

* Line 4 of the `float_to_int` function does not have a trailing `;` which is crucial to how the block is evaluated. I don't have any experience with Rust-like languages and found out only after a lot of confusing type-related errors when trying to implement the `missing test cases` exercises. You could call this out in the example here, but it would probably be a good idea to include it somewhere in the language reference.

* Simple Logic
* Missing test cases: it might be a good idea to show what the code looks like for these. My initial attempts to get it working resulted in hard-to-understand type errors because I had an extra `;` at the end of the last line of an evaluated else block (see above).