[Doc] Fix spelling of numerical and nightly in README.md (#6025)

Just a small change to fix spelling of numerical and nightly in
README.md

Related issue = #

Author: lokulin

README.md

@@ -20,7 +20,7 @@ Taichi Lang is an open-source, imperative, parallel programming language for hig
 
 <a href="https://github.com/taichi-dev/taichi/blob/master/python/taichi/examples/simulation/fractal.py#L1-L31"> <img src="https://github.com/taichi-dev/public_files/raw/master/taichi/fractal_code.png" height="270px"></a>  <img src="https://raw.githubusercontent.com/taichi-dev/public_files/master/taichi/fractal_small.gif" height="270px">
 
-The language has broad applications spanning real-time physical simulation, numberical computation, augmented reality, artificial intelligence, vision and robotics, visual effects in films and games, general-purpose computing, and much more.
+The language has broad applications spanning real-time physical simulation, numerical computation, augmented reality, artificial intelligence, vision and robotics, visual effects in films and games, general-purpose computing, and much more.
 
 <a href="https://github.com/taichi-dev/taichi/blob/master/python/taichi/examples/simulation/mpm128.py"><img src="https://github.com/taichi-dev/public_files/raw/master/taichi/mpm128.gif" height="192px"></a>
 <a href="https://github.com/taichi-dev/quantaichi"> <img src="https://raw.githubusercontent.com/taichi-dev/public_files/master/taichi/smoke_3d.gif" height="192px"></a>
@@ -69,7 +69,7 @@ Use Python's package installer **pip** to install Taichi Lang:
 pip install --upgrade taichi
 ```
 
-*We also provide a nightly package. Note that nighly packages may crash because they are not fully tested.  We cannot guarantee their validity, and you are at your own risk trying out our latest, untested features. The nightly packages can be installed from our self-hosted PyPI (Using self-hosted PyPI allows us to provide more frequent releases over a longer period of time)*
+*We also provide a nightly package. Note that nightly packages may crash because they are not fully tested.  We cannot guarantee their validity, and you are at your own risk trying out our latest, untested features. The nightly packages can be installed from our self-hosted PyPI (Using self-hosted PyPI allows us to provide more frequent releases over a longer period of time)*
 
 ```bash
 pip install -i https://pypi.taichi.graphics/simple/ taichi-nightly