doc: add style guide (#660)

Co-authored-by: Igor Matuszewski <[email protected]>

book/src/02_development/06_style_guide.md

@@ -0,0 +1,59 @@
+# Style Guide
+
+This is a style guide for the EDR project.
+
+## Procedural derive macros
+
+When deriving multiple traits, use the following rules to order them:
+
+1. Standard library traits before external crates
+2. Sub-traits before super-traits
+3. Alphabetical order
+
+For example:
+
+```rust
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+```
+
+Or, for sub- and super-traits:
+
+```rust
+#[derive(PartialEq, Eq, PartialOrd, Ord)]
+```
+
+## Member ordering
+
+When adding a variant to an `enum` or a field to a `struct` or enum variant, by default follow alphabetical order. If it makes more sense to follow custom ordering, feel free to do so.
+
+### Member functions
+
+For member functions, use the following default rules to order them:
+
+1. Public members before private members
+2. Alphabetical order
+
+Again, if it makes more sense to follow custom ordering, feel free to do so.
+
+### Example
+
+```rust
+struct Foo {
+    bar: u32,
+    baz: u32,
+}
+
+impl Foo {
+    pub fn bar_mut(&mut self) -> &mut u32 {
+        &mut self.bar
+    }
+
+    pub fn baz(&self) -> u32 {
+        self.baz
+    }
+
+    fn bar(&self) -> u32 {
+        self.bar
+    }
+}
+```

book/src/SUMMARY.md

@@ -15,6 +15,7 @@
   - [Local release](02_development/03_local_release.md)
   - [Update N-API targets](02_development/04_update_napi_targets.md)
   - [Using pnpm link](02_development/05_pnpm_link.md)
+  - [Style Guide](02_development/06_style_guide.md)
 
 - [Release](./03_release.md)