Mention SimPEG collaboration in docs (#65)

Mention SimPEG collaboration to build Choclo in the docs and in the
`README.md`.

README.md

@@ -10,7 +10,9 @@
 </p>
 
 <p align="center">
-Part of the <a href="https://www.fatiando.org"><strong>Fatiando a Terra</strong></a> project
+Part of the <a href="https://www.fatiando.org"><strong>Fatiando
+a Terra</strong></a> project, built in collaboration with <a
+href="https://simpeg.xyz"><strong>SimPEG</strong></a>
 </p>
 
 <p align="center">

doc/index.rst

@@ -27,10 +27,17 @@
 kernel functions for running geophysical forward and inverse models, intended
 to be used by other libraries as the underlying layer of their computation.
 
-"Choclo" is a term used in some countries of South America to refer to corn,
-originated from the `quechua
-<https://en.wikipedia.org/wiki/Quechuan_languages>`__
-word *chuqllu*.
+Choclo is part of the `Fatiando a Terra <https://www.fatiando.org/>`__ project,
+and built in collaboration with `SimPEG <https://simpeg.xyz>`__ with the goal
+of developing a common engine for running gravity and magnetic forward models.
+
+.. hint::
+
+   "Choclo" is a term used in some countries of South America to refer to corn,
+   originated from the `quechua
+   <https://en.wikipedia.org/wiki/Quechuan_languages>`__
+   word *chuqllu*.
+
 
 .. grid:: 1 2 1 2
     :margin: 5 5 0 0
@@ -91,11 +98,6 @@ word *chuqllu*.
             :outline:
             :expand:
 
-.. seealso::
-
-    Choclo is a part of the
-    `Fatiando a Terra <https://www.fatiando.org/>`__ project.
-
 
 .. toctree::
     :hidden:
@@ -136,3 +138,4 @@ word *chuqllu*.
     Code of Conduct <https://github.com/fatiando/choclo/blob/main/CODE_OF_CONDUCT.md>
     Source code on GitHub <https://github.com/fatiando/choclo>
     The Fatiando a Terra project <https://www.fatiando.org>
+    SimPEG <https://simpeg.xyz>

doc/overview.rst

@@ -12,8 +12,9 @@ modellings, sensitivity matrices calculations, equivalent sources
 implementations and more.
 
 These functions are not designed to be used by final users. Instead they are
-meant to be part of the underlaying engine of a higher level codebase, like
-`Harmonica <https://www.fatiando.org/harmonica>`__.
+meant to be part of the underlying engine of a higher level codebase, like
+`Harmonica <https://www.fatiando.org/harmonica>`__ and `SimPEG
+<https://docs.simpeg.xyz>`__.
 
 All Choclo functions rely on `Numba <https://numba.pydata.org/>`__ for
 just-in-time compilations, meaning that there's no need to distribute