Changes proposed in this pull request

• Adding intial vale configuration and start of ILF dictionary

Usage

1. vale sync
2. In the Vale VSCode extension, add the absolute path to the .vale.ini file in this repo:

3. Navigate to open-payments or rafiki and confirm the VSCode extension lints the md and mdx files

or if you don't want to use the extension, and your local directory is structured like so:

interledger
├── docs-styleguide
├── open-payments
├── rafiki

you can run vale from the CLI using:
cd open-payments
vale --config=../docs-styleguide/.vale.ini docs/

Context

Fixes #66