Add release page link and configuration flag to README

As Vanadia now already have stable release and binaries for Linux and
OSX in its GitHub release page, we should explain it in README to avoid
confusion (as apparently @xinuc is not aware that I've provided the
binaries).

Custom configuration file location is also supported in v1.1.0; it was
just not documented yet, so this is the time.

README.md

@@ -6,12 +6,26 @@ A utility to export [API Blueprint](https://github.com/apiaryio/api-blueprint) `
 
 ## Installation
 
+The latest executables for Linux and OSX are available from the [release page](https://github.com/bukalapak/vanadia/releases), so it can be executed directly:
+
+```sh
+$ wget https://github.com/bukalapak/vanadia/releases/download/${VERSION}/vanadia-${VERSION}.${OS}-amd64.tar.gz
+$ tar -xzf vanadia-${VERSION}.${OS}-amd64.tar.gz
+$ ./vanadia -h
+```
+
+### Manual build
+
+If you want to be in bleeding edge, you can manually build from `master`:
+
 ```sh
 $ git clone https://github.com/bukalapak/vanadia.git
 $ cd vanadia
 $ make
 ```
 
+Make sure you have Go 1.9 and build-essentials as we should compile [Drafter](https://github.com/apiaryio/drafter) as one of its dependency.
+
 ## Usage
 
 Let's say we have an API Blueprint document, `API.apib` in our working directory. Then we can do:
@@ -20,6 +34,14 @@ Let's say we have an API Blueprint document, `API.apib` in our working directory
 $ ./vanadia --input API.apib --output API.postman_collection.json
 ```
 
-## Configuration
+Vanadia can also read input from standard input and give its output via standard output; just omit the `--input` and `--output` flag.
+
+### Configuration
 
 Vanadia is configurable with a `vanadia.yml` in working directory. Please refer to `vanadia.yml` in this repository to see what is configurable.
+
+You can also configure Vanadia from other location by specifying the config file:
+
+```sh
+$ ./vanadia --input api/API.apib --output api/API.postman_collection.json --config api/vanadia.yml
+```