Fix some typos I noticed in the Programming Cryptol book. (#1631)

- p-1 bits in an IEEE float refers to the significand, not the
  mantissa, at least according to the latest preferred terminology,
  which aims to keep the word "mantissa" for the full mantissa
  including the units bit;
- reciprocal rather than reciprocol;
- the example in 1.23 had the wrong module declarations; also insert a
  separator word between the verbatim blocks so they can be told
  apart.

docs/ProgrammingCryptol/crashCourse/CrashCourse.tex

@@ -365,7 +365,7 @@ \section{Floating Point Numbers}
 
 The family of types \texttt{Float e p}\indTheFloatType represent IEEE 754
 floating point numbers with \texttt{e} bits in the exponent and
-\texttt{p-1} bits in the mantissa.  The family is defined in a built-in
+\texttt{p-1} bits in the significand.  The family is defined in a built-in
 module called \texttt{Float} so to use it you'd need to either import
 it in your Cryptol specification or use \texttt{:m Float} on the
 Cryptol REPL.
@@ -3206,7 +3206,7 @@ \section{Type classes}\indTypeClasses
 The \texttt{Field} typeclass represents values that, in addition to
 being a \texttt{Ring}, have multiplictive inverses.
 It includes the field division operation \texttt{/.} and the
-\texttt{recip} operation for computing the reciprocol of a value.
+\texttt{recip} operation for computing the reciprocal of a value.
 Currently, only type \texttt{Rational} is a member of this class.
 
 \item
@@ -3598,6 +3598,7 @@ \section{Program structure with modules}
 accordingly:
 
 \begin{verbatim}
+module Hash::SHA3 where
 
 sha3 : {n} (fin n) => [n] -> [512]
 sha3 = error "Stubbed, for demonstration only: sha3-512"
@@ -3606,8 +3607,10 @@ \section{Program structure with modules}
 blocksize = 576
 \end{verbatim}
 
+and
+
 \begin{verbatim}
-module Hash::SHA3 where
+module HMAC where
 import Hash::SHA3
 
 hmac : {keySize, msgSize} (fin keySize, fin msgSize) => [keySize] -> [msgSize] -> [512]