installation instruction uploaded

Doubt if the name should be consistent to lowercase, same with that in Python.

Doubt if we just directly point out the installation package path as we did after introducing "$Path", but get rid of "$Path" introduction.

Doubt if the folder storing the code should be renamed as "packages".

packages/Mathematica/INSTALL.md

@@ -0,0 +1,61 @@
+# Mathematica Front-End Installation Instructions #
+
+If you'd like to be able to use this package inside of any notebook, regardless
+of the notebook's location on your filesystem, then you can use Mathematica's
+front end to install this package. Use the following steps:
+
+1. Click `File -> Install...`
+2. Select `Package` for the _Type of Item to Install_
+3. Chose `From File...` for the _Source_
+4. Navigate to the `modernrobotics.m` and select it as the source for the package
+5. The _Install Name_ should default to `modernrobotics`; if it doesn't then
+   fill in the install name to be `modernrobotics`.
+6. Choose whether you want the package installed for a single user or for all
+   users (may require administrative privileges)
+7. Click `OK`
+
+Now from any notebook you should be able to load the library by running:
+
+```
+<<modernrobotics`
+```
+
+If you'd like to uninstall the package, you can just delete the file 
+`modernrobotics.wl` or `modernrobotics.m` in the following directory.
+
+```sh
+$MATHPATH/Applications/modernrobotics/
+```
+
+The value of `$MATHPATH` will depend on your system. You can determine it by
+looking at the `$Path` variable inside Mathematica. Here are some paths for
+common operating systems:
+
++ OS-X:                `~/Library/Mathematica/`
++ Linux (Debian):      `~/.Mathematica/`
++ Windows:             `%APPDATA%\Mathematica\`
+
+
+## Manual Installation Instructions ##
+
+If you have any troubles with the front-end installation described above, you
+can try manually installing the package by copying the `modernrobotics.m` file
+into the same directory mentioned for uninstalling.
+
+
+# Using the Package Locally #
+
+If you don't want to install the package at all, it is possible to place it
+anywhere on your filesystem and then load it into a notebook using
+
+```
+SetDirectory["<PATH-TO-DIRECTORY-CONTAINING-modernrobotics.m>"]
+<<modernrobotics`
+```
+
+If the notebook and the package are located in the same directory you could use 
+
+```
+SetDirectory[NotebookDirectory[]]
+<<modernrobotics`
+```