Add documentation sections for the #[enumcapsulate(discriminant(…))] attributes

Author: regexident

macros/README.md

@@ -105,6 +105,40 @@ then you can do so by use of an `#[enumcapsulate(exclude(…))]` attribute:
 enum Enum { /* ... */ }
 ```
 
+##### `#[enumcapsulate(discriminant(repr = …))]`
+
+Specify a memory representation for the generated discriminant type.
+
+> [!IMPORTANT]
+> This attribute is only recognized by the `VariantDiscriminant` derive macro.
+
+If you wish to specify a custom memory representation for the discriminant
+type generated by the `VariantDiscriminant` derive macro, then you can
+do so by use of an `#[enumcapsulate(discriminant(repr = <typename>))]` attribute:
+
+```rust
+#[derive(VariantDiscriminant)]
+#[enumcapsulate(discriminant(repr = u8))]
+enum MyEnum { /* ... */ }
+```
+
+##### `#[enumcapsulate(discriminant(name = …))]`
+
+Specify a custom name for the generated discriminant type.
+
+> [!IMPORTANT]
+> This attribute is only recognized by the `VariantDiscriminant` derive macro.
+
+If you wish to specify a custom name for the discriminant type
+generated by the `VariantDiscriminant` derive macro, then you can do
+so by use of an `#[enumcapsulate(discriminant(name = <typename>))]` attribute:
+
+```rust
+#[derive(VariantDiscriminant)]
+#[enumcapsulate(discriminant(name = MyDiscriminant))]
+enum MyEnum { /* ... */ }
+```
+
 ### Variant attributes
 
 > [!NOTE]
@@ -245,6 +279,48 @@ enum Enum {
 }
 ```
 
+##### `#[enumcapsulate(discriminant(value = …))]`
+
+Specify a memory representation for the generated discriminant type.
+
+> [!IMPORTANT]
+> This attribute is only recognized by the `VariantDiscriminant` derive macro.
+
+If you wish to specify a custom memory representation for the discriminant
+type generated by the `VariantDiscriminant` derive macro, then you can
+do so by use of an `#[enumcapsulate(discriminant(value = <expr>))]` attribute:
+
+```rust
+#[derive(VariantDiscriminant)]
+enum Enum {
+    #[enumcapsulate(discriminant(value = 42))]
+    VariantA(i32),
+    
+    VariantB { b: u32 },
+}
+```
+
+##### `#[enumcapsulate(discriminant(name = …))]`
+
+Specify a custom name for the generated discriminant type.
+
+> [!IMPORTANT]
+> This attribute is only recognized by the `VariantDiscriminant` derive macro.
+
+If you wish to specify a custom name for the discriminant type
+generated by the `VariantDiscriminant` derive macro, then you can do
+so by use of an `#[enumcapsulate(discriminant(name = …))]` attribute:
+
+```rust
+#[derive(VariantDiscriminant)]
+enum Enum {
+    #[enumcapsulate(discriminant(name = CustomDiscriminant))]
+    VariantA(i32),
+    
+    VariantB { b: u32 },
+}
+```
+
 ## Generics
 
 There is limited support for generic enums: