doc: spell check

* doc/bison.texi, NEWS, README-hacking.md: here.
And elsewhere.

NEWS

@@ -99,13 +99,13 @@ GNU Bison NEWS
   To avoid the confusion with typing in programming languages, we now refer
   to token and symbol "kinds" instead of token and symbol "types".
 
-**** Token kind
+**** Token kinds
 
   The "token kind" is what is returned by the scanner, e.g., PLUS, NUMBER,
   LPAREN, etc.  Users are invited to replace their uses of "enum
   yytokentype" by "yytoken_kind_t".
 
-  This type now also includes tokens that were proviously hidden: YYEOF (end
+  This type now also includes tokens that were previously hidden: YYEOF (end
   of input), YYUNDEF (undefined token), and YYERRCODE (error token).  They
   now have string aliases, internationalized if internationalization is
   enabled.  Therefore, by default, error messages now refer to "end of file"
@@ -121,11 +121,13 @@ GNU Bison NEWS
 **** Symbol kinds
 
   The "symbol kinds" is what the parser actually uses.  (Unless the
-  api.token.raw %define variable was used, the internal symbol kind of a
-  terminal differs from the corresponding token kind.)
+  api.token.raw %define variable is used, the symbol kind of a terminal
+  differs from the corresponding token kind.)
 
   They are now exposed as a enum, "yysymbol_kind_t".
 
+  This allows users to tailor the error messages the way they want.
+
 *** Modernize display of explanatory statements in diagnostics
 
   Since Bison 2.7, output was indented four spaces for explanatory
@@ -4077,9 +4079,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
  LocalWords:  noexcept constexpr ispell american deprecations backend Teoh
  LocalWords:  YYPRINT Mangold Bonzini's Wdangling exVal baz checkable gcc
  LocalWords:  fsanitize Vogelsgesang lis redeclared stdint automata yytname
- LocalWords:  yysymbol yytnamerr yyreport ctx ARGMAX yysyntax stderr
- LocalWords:  symrec yypcontext TOKENMAX yyexpected YYEMPTY yypstate
+ LocalWords:  yysymbol yytnamerr yyreport ctx ARGMAX yysyntax stderr LPAREN
+ LocalWords:  symrec yypcontext TOKENMAX yyexpected YYEMPTY yypstate YYEOF
  LocalWords:  autocompletion bistromathic submessages Cayuela lexcalc
+ LocalWords:  yytoken YYUNDEF YYERRCODE
 
 Local Variables:
 ispell-dictionary: "american"