Updated README.md Grammar
Suggested appropriate changes in grammar.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] Ensure all linting tests pass, see [here](https://pandas.pydata.org/pandas-docs/dev/development/contributing.html#code-standards) for how to run them
- [ ] whatsnew entry

some of these changes were already suggested in #42454. It was closed, however, since those/these changes are not grammatical errors, they are more subjective preferences of the author and changes are not needed. Agree that these changes are not needed - please see [good first issues](https://github.com/pandas-dev/pandas/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22) and [contributing guide](https://pandas.pydata.org/docs/development/contributing.html) for how to contribute to pandas