Merge pull request #905 from TheBlueMatt/2021-04-mention-invoice-storage-docs

Mention storage req for users with a public invoice generation API

diff --combined lightning/src/ln/channelmanager.rs
index 451bf8be4a1cf02a74e4daa189658e59d8e05d98,58b6982c42a94331578f7cd61d967e9830ce13d5..439c9b93c27af37858a783147dd796f5b6aa7746
--- 1/lightning/src/ln/channelmanager.rs
--- 2/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@@ -68,6 -68,7 +68,6 @@@ use std::sync::atomic::{AtomicUsize, Or
  use std::time::Duration;
  #[cfg(any(test, feature = "allow_wallclock_use"))]
  use std::time::Instant;
 -use std::marker::{Sync, Send};
  use std::ops::Deref;
  use bitcoin::hashes::hex::ToHex;
  
@@@ -3467,6 -3468,10 +3467,10 @@@ impl<Signer: Sign, M: Deref, T: Deref, 
        /// If you need exact expiry semantics, you should enforce them upon receipt of
        /// [`PaymentReceived`].
        ///
+       /// Pending inbound payments are stored in memory and in serialized versions of this
+       /// [`ChannelManager`]. If potentially unbounded numbers of inbound payments may exist and
+       /// space is limited, you may wish to rate-limit inbound payment creation.
+       ///
        /// May panic if `invoice_expiry_delta_secs` is greater than one year.
        ///
        /// Note that invoices generated for inbound payments should have their `min_final_cltv_expiry`
@@@ -3763,7 -3768,7 +3767,7 @@@ wher
        }
  }
  
 -impl<Signer: Sign, M: Deref + Sync + Send, T: Deref + Sync + Send, K: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send>
 +impl<Signer: Sign, M: Deref , T: Deref , K: Deref , F: Deref , L: Deref >
        ChannelMessageHandler for ChannelManager<Signer, M, T, K, F, L>
        where M::Target: chain::Watch<Signer>,
          T::Target: BroadcasterInterface,