fix(cli): better explanations for --interfaces

cli/options/src/lib.rs

@@ -125,14 +125,14 @@ pub struct FStarOptions {
     #[arg(long, default_value = "1")]
     ifuel: u32,
     /// Modules for which Hax should extract interfaces (`*.fsti`
-    /// files). By default we extract no interface. This flag expects
-    /// a space-separated list of inclusion clauses. An inclusion
-    /// clause is a Rust path prefixed with `+`, `+!` or `-`. `-`
-    /// excludes any matched item, `+` includes any matched item, `+!`
-    /// extracts only an interface and drops its implementation. By
-    /// default, every item is included. Rust path chunks can be
-    /// either a concrete string, or a glob (just like bash globs, but
-    /// with Rust paths).
+    /// files) in supplement to implementations (`*.fst` files). By
+    /// default we extract no interface, only implementations. This
+    /// flag expects a space-separated list of inclusion clauses. An
+    /// inclusion clause is a Rust path prefixed with `+`, `+!` or
+    /// `-`. `-` means implementation only, `+!` means interface only
+    /// and `+` means implementation and interface. Rust path chunks
+    /// can be either a concrete string, or a glob (just like bash
+    /// globs, but with Rust paths).
     #[arg(
         long,
         value_parser = parse_inclusion_clause,