Update changelog.

zcash_primitives/CHANGELOG.md

@@ -16,6 +16,13 @@ and this library adheres to Rust's notion of
   to provide range values for branch active heights.
 - `zcash_primitives::consensus::NetworkUpgrade::Nu5` value representing the Nu5 upgrade.
 - `zcash_primitives::consensus::BranchId::Nu5` value representing the Nu5 consensus branch.
+- `zcash_primitives::transaction::components::sapling::builder` builder for Sapling 
+  transaction components
+- `zcash_primitives::transaction::components::transparent::builder` builder for transparent 
+  transaction components
+- `zcash_primitives::transaction::components::tze::builder` builder for TZE 
+  transaction components
+
 ### Changed
 - MSRV is now 1.51.0.
 - The following modules and helpers have been moved into
@@ -36,6 +43,17 @@ and this library adheres to Rust's notion of
   now taxes a TxId rather than a raw byte array.
 - `zcash_primitives::transaction::components::Amount` addition, subtraction,
   and summation now return `Option` rather than panicing on overflow.
+- `zcash_primitives::transaction::builder::Error` has been modified to
+  wrap the error types produced by its child builders.
+- `zcash_primitives::transaction::builder::Builder` now delegates to the
+  newly created child builder components.
+- `zcash_primitives::transaction::builder::Builder::build` now takes the 
+  version of the transaction being constructed as an argument. Instead of
+  constructing an empty transaction and mutating that transaction through
+  a series of build steps, the individual component builders construct
+  parts of the transaction independently and then these parts are brought
+  together to construct a new `TransactionData` value prior to the generation 
+  of signatures.
 
 ## [0.5.0] - 2021-03-26
 ### Added