fix(docs): Correct typos in README.md

[nishioka-shinji]

Hi maintainers,

I noticed a couple of minor typos in the README.md while reading through the documentation. This small PR fixes them.

Changes

1. Spelling error in heading:
   In the "Complex processing options" section, the subheading Using named arguments with usupported options has been corrected to Using named arguments with unsupported options.

2. Syntax error in code example:
   In the "Unnamed arguments" section, the code example for trim had a syntax error (1. 1 instead of 1, 1). This has been corrected to match the resulting URL example shown below it.

This is just a documentation fix and introduces no functional changes.

Cheers!