Update README.md with "read-only" information

Mention that API is read-only in the first paragraph of README.md.

Author: Electronic-Mango

README.md

@@ -5,7 +5,7 @@
 [![Flake8](https://github.com/Electronic-Mango/reddit-python-api/actions/workflows/flake8.yml/badge.svg)](https://github.com/Electronic-Mango/reddit-api-api/actions/workflows/flake8.yml)
 [![PyPI version](https://badge.fury.io/py/reddit-python-api.svg)](https://badge.fury.io/py/reddit-python-api)
 
-A simple Reddit Python API allowing accessing both subreddit and user submissions, build with [`httpx`](https://www.python-httpx.org/).
+A simple read-only Reddit Python API allowing access to both subreddit and user submissions, build with [`httpx`](https://www.python-httpx.org/).