Update the README

Author: rlouf

README.md

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+<div align="center">
+
+<img src="./doc/images/aesara_logo_2400.png" alt="logo"></img>
+
+[![Pypi][pypi-badge]][pypi]
+[![Downloads][downloads-badge]][releases]
+[![Contributors][contributors-badge]][contributors]
+ </br>
+[![Gitter][gitter-badge]][gitter]
+[![Discord][discord-badge]][discord]
+[![Twitter][twitter-badge]][twitter]
+
+Aesara is a Python library that allows one to define, optimize, and
+efficiently evaluate mathematical expressions involving multi-dimensional
+arrays.
+
+[Features](#features) •
+[Get Started](#get-started) •
+[Installation](#installation) •
+[Get help](#get-help) •
+[Contribute](#contribute)
+
+</div>
+
+## Features
+
+- A hackable, pure-Python codebase
+- Extensible graph framework suitable for rapid development of custom operators and symbolic optimizations
+- Implements an extensible graph transpilation framework that currently provides
+  compilation via C, [JAX](https://github.com/google/jax), and [Numba](https://github.com/numba/numba).
+- Based on one of the most widely-used Python tensor libraries: [Theano](https://github.com/Theano/Theano).
+
+## Get started
+
+``` python
+import aesara
+from aesara import tensor as at
+
+# Declare two symbolic floating-point scalars
+a = at.dscalar("a")
+b = at.dscalar("b")
+
+# Create a simple example expression
+c = a + b
+
+# Convert the expression into a callable object that takes `(a, b)`
+# values as input and computes the value of `c`.
+f_c = aesara.function([a, b], c)
+
+assert f_c(1.5, 2.5) == 4.0
+
+# Compute the gradient of the example expression with respect to `a`
+dc = aesara.grad(c, a)
+
+f_dc = aesara.function([a, b], dc)
+
+assert f_dc(1.5, 2.5) == 1.0
+
+# Compiling functions with `aesara.function` also optimizes
+# expression graphs by removing unnecessary operations and
+# replacing computations with more efficient ones.
+
+v = at.vector("v")
+M = at.matrix("M")
+
+d = a/a + (M + a).dot(v)
+
+aesara.dprint(d)
+# Elemwise{add,no_inplace} [id A] ''
+#  |InplaceDimShuffle{x} [id B] ''
+#  | |Elemwise{true_div,no_inplace} [id C] ''
+#  |   |a [id D]
+#  |   |a [id D]
+#  |dot [id E] ''
+#    |Elemwise{add,no_inplace} [id F] ''
+#    | |M [id G]
+#    | |InplaceDimShuffle{x,x} [id H] ''
+#    |   |a [id D]
+#    |v [id I]
+
+f_d = aesara.function([a, v, M], d)
+
+# `a/a` -> `1` and the dot product is replaced with a BLAS function
+# (i.e. CGemv)
+aesara.dprint(f_d)
+# Elemwise{Add}[(0, 1)] [id A] ''   5
+#  |TensorConstant{(1,) of 1.0} [id B]
+#  |CGemv{inplace} [id C] ''   4
+#    |AllocEmpty{dtype='float64'} [id D] ''   3
+#    | |Shape_i{0} [id E] ''   2
+#    |   |M [id F]
+#    |TensorConstant{1.0} [id G]
+#    |Elemwise{add,no_inplace} [id H] ''   1
+#    | |M [id F]
+#    | |InplaceDimShuffle{x,x} [id I] ''   0
+#    |   |a [id J]
+#    |v [id K]
+#    |TensorConstant{0.0} [id L]
+
+```
+
+See [the Aesara documentation][documentation] for in-depth tutorials.
+
+## Installation
+
+The latest release of Aesara can be installed from PyPI using ``pip``:
+
+``` python
+pip install aesara
+```
+
+Or via conda-forge:
+
+``` python
+conda install -c conda-forge aesara
+```
+
+
+The current development branch of Aesara can be installed from GitHub, also using ``pip``:
+
+``` python
+pip install git+https://github.com/aesara-devs/aesara
+```
+
+
+## Get help
+
+Report bugs by opening an [issue][issues]. If you have a question regarding the usage of Aesara, start a [discussion][discussions]. For real-time feedback or more general chat about Aesara use our [Discord server][discord], or [Gitter][gitter].
+
+## Contribute
+
+We welcome bug reports and fixes and improvements to the documentation.
+
+For more information on contributing, please see the
+[contributing guide](https://github.com/aesara-devs/aesara/blob/main/CONTRIBUTING.md)
+and the Aesara [Mission Statement](https://github.com/aesara-devs/aesara/mission.rst).
+
+A good place to start contributing is by looking through [the issues][issues].
+
+## Support
+
+Special thanks to [Bram Timmer](http://beside.ca) for the logo.
+
+[contributors]: https://github.com/aesara-devs/aesara/graphs/contributors
+[contributors-badge]: https://img.shields.io/github/contributors/aesara-devs/aesara?style=flat-square&logo=github&logoColor=white&color=ECEFF4
+[discussions]: https://github.com/aesara-devs/aesara/discussions
+[documentation]: https://aesara.readthedocs.io/en/latest
+[downloads-badge]: https://img.shields.io/pypi/dm/aesara?style=flat-square&logo=pypi&logoColor=white&color=8FBCBB
+[discord]: https://discord.gg/h3sjmPYuGJ
+[discord-badge]: https://img.shields.io/discord/1072170173785723041?color=81A1C1&logo=discord&logoColor=white&style=flat-square
+[gitter]: https://gitter.im/aesara-devs/aesara
+[gitter-badge]: https://img.shields.io/gitter/room/aesara-devs/aesara?color=81A1C1&logo=matrix&logoColor=white&style=flat-square
+[issues]: https://github.com/aesara-devs/aesara/issues
+[releases]: https://github.com/aesara-devs/aesara/releases
+[twitter]: https://twitter.com/AesaraDevs
+[twitter-badge]: https://img.shields.io/twitter/follow/AesaraDevs?style=social
+[pypi]: https://pypi.org/project/aesara/
+[pypi-badge]: https://img.shields.io/pypi/v/aesara?color=ECEFF4&logo=python&logoColor=white&style=flat-square