Added docs for rust backend

docs/backend/README.md

@@ -0,0 +1,84 @@
+# BingoBongo Backend
+
+## JSON API
+
+### Objects
+
+---
+BingoSquare
+```json
+{
+    "option": "String"
+}
+```
+---
+BingoBoard
+```json
+{
+    "size": 9,
+    "squares": [
+        <BingoSquare>,
+        <BingoSquare>,
+        ...,
+        <BingoSquare>
+    ]
+}
+```
+---
+Meta
+```json
+{
+    "name": "String",
+    "description": "String"
+}
+```
+---
+BingoPool
+```json
+{
+    "meta": Meta,
+    "squares": [
+        <BingoSquare>,
+        <BingoSquare>,
+        ...,
+        <BingoSquare>
+    ]
+}
+```
+
+
+## Config
+Config is loaded from `~/.local/bingobongo.toml`
+
+Config default is:
+```toml
+working_dir = "/path/to/working/dir"
+```
+
+## Running
+Currently the backend loads the bingo datasets from the `{working_dir}/pools/` directory, they are just toml files with the following syntax
+
+```toml
+[meta]
+name = 'Name of pool'
+description = 'Description of pool'
+
+[[squares]]
+option = 'First square'
+
+[[squares]]
+option = 'Second square'
+
+[[squares]]
+option = 'Third square'
+
+[[squares]]
+option = 'Fourth square'
+
+[[squares]]
+option = 'Fifth square'
+```
+
+Having the same header `[[]]` puts them in a list
+
+Both the config and a single dataset is required