Merge rust-bitcoin/rust-bitcoin#2527: Tidy description

e3db95226a Tidy description (yancy)

Pull request description:

  I noticed `uncheced_add` looked really bad with two spaces (my mistake).  Fixed some others as well.

ACKs for top commit:
  apoelstra:
    ACK e3db95226a oops, we should have caught this. Thanks for the fix!
  tcharding:
    ACK e3db95226a

Tree-SHA512: 8a2e7f85262f17063bea6ac22855ae45d99a1559a2d30f2627ffba1108f0fd8ebd0b541b50fe746b5af2ebb013cb3e9ea432987b90f37c046120388a808c5443

units/src/amount.rs

@@ -988,34 +988,38 @@ impl Amount {
     // Some arithmetic that doesn't fit in `core::ops` traits.
 
     /// Checked addition.
+    ///
     /// Returns [None] if overflow occurred.
     pub fn checked_add(self, rhs: Amount) -> Option<Amount> {
         self.0.checked_add(rhs.0).map(Amount)
     }
 
     /// Checked subtraction.
+    ///
     /// Returns [None] if overflow occurred.
     pub fn checked_sub(self, rhs: Amount) -> Option<Amount> {
         self.0.checked_sub(rhs.0).map(Amount)
     }
 
     /// Checked multiplication.
+    ///
     /// Returns [None] if overflow occurred.
     pub fn checked_mul(self, rhs: u64) -> Option<Amount> { self.0.checked_mul(rhs).map(Amount) }
 
     /// Checked integer division.
+    ///
     /// Be aware that integer division loses the remainder if no exact division
     /// can be made.
     /// Returns [None] if overflow occurred.
     pub fn checked_div(self, rhs: u64) -> Option<Amount> { self.0.checked_div(rhs).map(Amount) }
 
     /// Checked remainder.
+    ///
     /// Returns [None] if overflow occurred.
     pub fn checked_rem(self, rhs: u64) -> Option<Amount> { self.0.checked_rem(rhs).map(Amount) }
 
     /// Unchecked addition.
     ///
-    ///
     /// Computes `self + rhs`.  Panics in debug mode, wraps in release mode.
     pub fn unchecked_add(self, rhs: Amount) -> Amount {
         Self(self.0 + rhs.0)