Fix typographical errors in documentation

[Marcofann]

This pull request resolves typographical errors across three files: README.md, conversion.rs, and msgpack.rs. The changes enhance clarity and grammatical correctness in documentation and inline comments without altering functionality.

Summary of Changes

1. README.md

   • Corrected "a initialized" to "an initialized."
   • Fixed "up an running" to "up and running."

2. conversion.rs

   • Changed "a unsigned int" to "an unsigned int" for grammatical accuracy.

3. msgpack.rs

   • Adjusted "a 8-bit unsigned integer" to "an 8-bit unsigned integer."
   • Updated "a 8-bit signed integer" to "an 8-bit signed integer."

[chipshort]

Thanks