📝 Update readme accordingly

Author: wrenger

README.md

@@ -97,10 +97,11 @@ struct MyBitfield {
     /// sign extend for signed integers
     #[bits(13)]
     negative: i16,
-    /// supports any type, with `into`/`from` expressions (that are const eval)
+    /// supports any type, with `into_bits`/`from_bits` (const) functions,
+    /// if not configured otherwise with the `into`/`from` parameters of the bits attribute.
     ///
-    /// the field is initialized with 0 (passed into `from`) if not specified otherwise
-    #[bits(16, into = this as _, from = CustomEnum::from_bits(this))]
+    /// the field is initialized with 0 (passed into `from_bits`) if not specified otherwise
+    #[bits(16)]
     custom: CustomEnum,
     /// public field -> public accessor functions
     #[bits(12)]
@@ -119,7 +120,10 @@ enum CustomEnum {
     C = 2,
 }
 impl CustomEnum {
-    // This has to be const eval
+    // This has to be a const fn
+    const fn into_bits(self) -> u64 {
+        self as _
+    }
     const fn from_bits(value: u64) -> Self {
         match value {
             0 => Self::A,