Remove doc(hidden) from error conversion functions

Give people access to the error type conversion docs, its no harm and it
may be useful when the compiler does not give enough information.

bitcoin/src/address.rs

@@ -148,12 +148,10 @@ impl std::error::Error for Error {
     }
 }
 
-#[doc(hidden)]
 impl From<base58::Error> for Error {
     fn from(e: base58::Error) -> Error { Error::Base58(e) }
 }
 
-#[doc(hidden)]
 impl From<bech32::Error> for Error {
     fn from(e: bech32::Error) -> Error { Error::Bech32(e) }
 }

bitcoin/src/blockdata/script/mod.rs

@@ -779,7 +779,6 @@ impl From<UintError> for Error {
 }
 
 #[cfg(feature = "bitcoinconsensus")]
-#[doc(hidden)]
 impl From<bitcoinconsensus::Error> for Error {
     fn from(err: bitcoinconsensus::Error) -> Error { Error::BitcoinConsensus(err) }
 }

bitcoin/src/consensus/encode.rs

@@ -93,7 +93,6 @@ impl std::error::Error for Error {
     }
 }
 
-#[doc(hidden)]
 impl From<io::Error> for Error {
     fn from(error: io::Error) -> Self { Error::Io(error) }
 }

bitcoin/src/crypto/key.rs

@@ -65,17 +65,14 @@ impl std::error::Error for Error {
     }
 }
 
-#[doc(hidden)]
 impl From<base58::Error> for Error {
     fn from(e: base58::Error) -> Error { Error::Base58(e) }
 }
 
-#[doc(hidden)]
 impl From<secp256k1::Error> for Error {
     fn from(e: secp256k1::Error) -> Error { Error::Secp256k1(e) }
 }
 
-#[doc(hidden)]
 impl From<hex::Error> for Error {
     fn from(e: hex::Error) -> Self { Error::Hex(e) }
 }

bitcoin/src/psbt/error.rs

@@ -203,7 +203,6 @@ impl std::error::Error for Error {
     }
 }
 
-#[doc(hidden)]
 impl From<hashes::FromSliceError> for Error {
     fn from(e: hashes::FromSliceError) -> Error { Error::HashParse(e) }
 }

bitcoin/src/sign_message.rs

@@ -68,7 +68,6 @@ mod message_signing {
         }
     }
 
-    #[doc(hidden)]
     impl From<secp256k1::Error> for MessageSignatureError {
         fn from(e: secp256k1::Error) -> MessageSignatureError {
             MessageSignatureError::InvalidEncoding(e)