Proposing a PR to fix a few small typos

# Issue Type

[x] Bug (Typo)

# Steps to Replicate and Expected Behaviour

- Examine README.md and observe `syncronous`, however expect to see `synchronous`.
- Examine README.md and observe `semplicity`, however expect to see `simplicity`.

# Notes

Semi-automated issue generated by
https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

To avoid wasting CI processing resources a branch with the fix has been
prepared but a pull request has not yet been created. A pull request fixing
the issue can be prepared from the link below, feel free to create it or
request @timgates42 create the PR. Alternatively if the fix is undesired please
close the issue with a small comment about the reasoning.

https://github.com/timgates42/unirest-python/pull/new/bugfix_typos

Thanks.

Open README.md and locate the misspellings `syncronous` and `semplicity` identified in the issue. Correct them to `synchronous` and `simplicity`, then review the README to confirm both instances are fixed and no unintended text changed.

Written by the indexing model from the issue text.