Add description to span crate manifest

Author: lnicola

crates/span/Cargo.toml

@@ -1,6 +1,8 @@
 [package]
 name = "span"
 version = "0.0.0"
+description = "TBD"
+
 rust-version.workspace = true
 edition.workspace = true
 license.workspace = true
@@ -18,4 +20,4 @@ syntax.workspace = true
 stdx.workspace = true
 
 [lints]
-workspace = true
+workspace = true