docs(readme): Added an actual readme (#14)

Readme.md

@@ -1,7 +1,62 @@
 # git-ignore
 
-## Dependencies
+A CLI tool for Git to generate `.gitignore` files for your repository.
+
+One common issue when setting up a new Git repository is that at some
+point you need to create a `.gitignore` file to make sure that certain
+files aren't ever commited. For example, some generated files (`.o`)
+or editor specific files (`.swp`/`.swo`). Writing these files isn't
+hard but tends to be error prone (did you forget to include a specific
+file? Do you know all the files you need to exclude?). Now there are
+some solutions to help with this such as
+[gitignore.io](https://gitignore.io) or the
+[gitignore project](https://github.com/github/gitignore) but both
+options have their own problems. gitignore.io requires you to
+copy/paste around the file contents that you need and doesn't support
+a ton of different services/languages. The gitignore repository does
+support a lot of things you might want to ignore but its annoying to
+use since you have to dig through all the files to find what you need.
+This project works to solve all of those problems by providing a
+simple CLI command that can generate a file with a single line.
+
+`git ignore generate C C++ > .gitignore`
+
+You can see all available options for the `generate` command with the
+`list` command.
+
+`git ignore list`
+
+## Install
+
+Installation should be pretty straight forward. Just head on over to
+the [releases page](https://github.com/durandj/git-ignore/releases)
+and download the latest version for your desired platform, mark it
+as executable (if on a Unix type system) and put it somewhere on your
+`PATH`.
+
+For example, if I wanted to install version `latest` (this isn't a
+real version) for 64 bit Linux I would do:
+
+```
+wget https://github.com/durandj/git-ignore/releases/download/vLatest/git-ignore_vLatest_linux_amd64
+chmod +x git-ignore_vLatest_linux_amd64
+sudo mv git-ignore_vLatest_linux_amd64 /usr/local/bin
+```
+
+## Developing
+
+Make sure you first install the following dependencies:
+
+### Dependencies
 
  * Golang 1.11+
  * [Ginkgo](http://onsi.github.io/ginkgo/)
  * [Taskfile](https://taskfile.org)
+
+### Tasks
+
+Taskfile provides a way of running different scripts easily (similar
+to how Makefiles work but better).
+
+To build the code you can just do `task build`.
+To run tests run `task test`.