add comment explaining why range syntax is not valid

Author: Emilgardis

svd-rs/src/dimelement.rs

@@ -170,6 +170,8 @@ impl DimElement {
     pub fn indexes_as_range(&self) -> Option<RangeInclusive<u32>> {
         let mut integers = Vec::with_capacity(self.dim as usize);
         for idx in self.indexes() {
+            // XXX: indexes that begin with leading zero are not compatible with range (`0-x`) syntax in serialization
+            // see https://github.com/rust-embedded/svdtools/pull/178#issuecomment-1801433808
             let val = idx.parse::<u32>().ok()?;
             if val.to_string() != idx {
                 return None;