Fix dead links to the tokenizer's source code (#1250)

developer-workflow/grammar.rst

@@ -42,7 +42,7 @@ Note: sometimes things mysteriously don't work.  Before giving up, try ``make cl
   Then run ``make regen-ast`` to regenerate
   :cpy-file:`Include/internal/pycore_ast.h` and :cpy-file:`Python/Python-ast.c`.
 
-* :cpy-file:`Parser/tokenizer.c` contains the tokenization code.
+* :cpy-file:`Parser/lexer/` contains the tokenization code.
   This is where you would add a new type of comment or string literal, for example.
 
 * :cpy-file:`Python/ast.c` will need changes to validate AST objects

internals/compiler.rst

@@ -11,7 +11,7 @@ Abstract
 
 In CPython, the compilation from source code to bytecode involves several steps:
 
-1. Tokenize the source code (:cpy-file:`Parser/tokenizer.c`).
+1. Tokenize the source code (:cpy-file:`Parser/lexer/` and :cpy-file:`Parser/tokenizer/`).
 2. Parse the stream of tokens into an Abstract Syntax Tree
    (:cpy-file:`Parser/parser.c`).
 3. Transform AST into an instruction sequence (:cpy-file:`Python/compile.c`).

internals/parser.rst

@@ -599,8 +599,9 @@ If you are on Windows you can use the Visual Studio project files to regenerate
 
     ./PCbuild/build.bat --regen
 
-How tokens are generated and the rules governing this is completely up to the tokenizer (:cpy-file:`Parser/tokenizer.c`)
-and the parser just receives tokens from it.
+How tokens are generated and the rules governing this are completely up to the tokenizer
+(:cpy-file:`Parser/lexer/` and :cpy-file:`Parser/tokenizer/`);
+the parser just receives tokens from it.
 
 Memoization
 -----------