Make lightning-transaction-sync compat notice a bit more explicit

As `lightning-transaction-sync` was introduced with 0.0.114 and depended
on prior changes in the same release cycle we deemed it reasonable to
omit the implicitly limited backwards compatibility.

It however turns out this might be confusing to users copy/pasting the
codebase. Here we therefore spell out the implicit dependency on 0.0.114
and above.

Author: tnull

lightning-transaction-sync/src/lib.rs

@@ -13,7 +13,8 @@
 //!
 //! ## Version Compatibility
 //!
-//! Currently this crate is compatible with nodes that were created with LDK version 0.0.113 and above.
+//! Currently this crate is compatible with nodes that were created with LDK version 0.0.114 and
+//! above and channels that were created with LDK version 0.0.113 and above.
 //!
 //! ## Usage Example:
 //!