Add documentation to README.

Signed-off-by: Vaibhav <[email protected]>

README.md

@@ -1,3 +1,88 @@
 # leaf
 
 > General purpose hot-reloader for all projects.
+
+## Contents
+
+1. [Installation](#installation)
+1. [Usage](#usage)
+    1. [Command line help](#command-line-help)
+    1. [Configuration file](#configuration-file)
+
+## Installation
+
+1. Clone the repository and `cd` into it.
+1. Run `make build` to build the leaf as `build/leaf`.
+1. Move the binary somewhere in your `$PATH`.
+
+## Usage
+
+### Command line help
+
+```console
+> leaf --help
+Given a set of commands, leaf watches the filtered paths in the project directory for any changes and runs the commands in
+order so you don't have to yourself
+
+Usage:
+  leaf [flags]
+  leaf [command]
+
+Available Commands:
+  help        Help about any command
+  version     Leaf version
+
+Flags:
+  -c, --config string   Config path for leaf configuration file (default "<CWD>/.leaf.yml")
+  -h, --help            help for leaf
+
+Use "leaf [command] --help" for more information about a command.
+```
+
+### Configuration file
+
+This project doesn't really require a hot-reload but a sample hot-reload for this project would look like [this](_examples/sample.leaf.yml):
+
+```yaml
+# Leaf configuration file.
+
+# Root directory to watch.
+# Defaults to current working directory.
+root: "."
+
+# Exclude directories while watching.
+# If certain directories are not excluded, it might reach a limitation where watcher doesn't start.
+exclude:
+  - ".git/"
+  - "vendor/"
+  - "build/"
+
+# Filters to apply on the watch.
+# Filters starting with '+' are includent and then with '-' are excluded.
+# This is not like exclude, these are still being watched yet can be excluded from the execution.
+# These can include any filepath regex supported by "filepath".Match method or even a directory.
+filters:
+  - "- .git*"
+  - "- .go*"
+  - "- .golangci.yml"
+  - "- go.*"
+  - "- Makefile"
+  - "- LICENSE"
+  - "- README.md"
+
+# Commands to be executed.
+# These are run in the provided order.
+exec:
+  - ["make", "build"]
+
+# Delay after which commands are executed.
+delay: '1s'
+```
+
+By default the config path is taken as `<current working directory>/.leaf.yml` which you can change using the `--config` or `-c` flag. You can also use a JSON or TOML file. Just remember to use "delay" in nanoseconds (seconds * 10^9).
+
+---
+
+Made with **khoon**, **paseena** and **love** `:-)` by
+
+Vaibhav ([vrongmeal](https://vrongmeal.github.io))