📝 Add additional installation information to README (#233)

* Add additional installation information to README (#232)

* 📝 Update README.md

---------

Co-authored-by: Omar Ali Khan <omar.khan@anvilogic.com>
Co-authored-by: Yasser Tahiri <yasserth19@gmail.com>

README.md

@@ -8,3 +8,17 @@
 A place for pydantic types that probably shouldn't exist in the main pydantic lib.
 
 See [pydantic/pydantic#5012](https://github.com/pydantic/pydantic/issues/5012) for more info.
+
+## Installation
+
+Install this library with the desired extras dependencies as listed in [project.optional-dependencies](./pyproject.toml).
+
+For example, if pendulum support was desired:
+
+```shell
+# via uv
+$ uv add "pydantic-extra-types[pendulum]"
+
+# via pip
+$ pip install -U "pydantic-extra-types[pendulum]"
+```