BIP77: remove redundant sentence line (#1858)

Author: jonatack

bip-0077.md

@@ -185,7 +185,6 @@ transaction flows.
 
 A `req-pj` parameter may be used as a [BIP 21 forwards compatibility `reqparam`](https://github.com/bitcoin/bips/blob/master/bip-0021.mediawiki#forward-compatibility) instead of
 `pj` to signal that Payjoin is required.
-`pj` to signal that Payjoin is required.
 
 The parameter value must be [uppercased and the parameter should be placed last in the URI](#uppercase-url).