chore: update generated file headers to reference wren_to_c_string.py

Replace the generic "Do not edit" comment in all five `.wren.inc` files with a
more informative preamble that explicitly names the source `.wren` file and the
`util/wren_to_c_string.py` generator script, and update the script's own
`PREAMBLE` template accordingly.

src/module/io.wren.inc

@@ -1,4 +1,6 @@
-// Generated automatically from src/module/io.wren. Do not edit.
+// Please do not edit this file. It has been generated automatically
+// from `src/module/io.wren` using `util/wren_to_c_string.py`
+
 static const char* ioModuleSource =
 "import \"scheduler\" for Scheduler\n"
 "\n"

src/module/os.wren.inc

@@ -1,4 +1,6 @@
-// Generated automatically from src/module/os.wren. Do not edit.
+// Please do not edit this file. It has been generated automatically
+// from `src/module/os.wren` using `util/wren_to_c_string.py`
+
 static const char* osModuleSource =
 "class Platform {\n"
 "  foreign static isPosix\n"

src/module/repl.wren.inc

@@ -1,4 +1,6 @@
-// Generated automatically from src/module/repl.wren. Do not edit.
+// Please do not edit this file. It has been generated automatically
+// from `src/module/repl.wren` using `util/wren_to_c_string.py`
+
 static const char* replModuleSource =
 "import \"meta\" for Meta\n"
 "import \"io\" for Stdin, Stdout\n"

src/module/scheduler.wren.inc

@@ -1,4 +1,6 @@
-// Generated automatically from src/module/scheduler.wren. Do not edit.
+// Please do not edit this file. It has been generated automatically
+// from `src/module/scheduler.wren` using `util/wren_to_c_string.py`
+
 static const char* schedulerModuleSource =
 "class Scheduler {\n"
 "  static add(callable) {\n"

src/module/timer.wren.inc

@@ -1,4 +1,6 @@
-// Generated automatically from src/module/timer.wren. Do not edit.
+// Please do not edit this file. It has been generated automatically
+// from `src/module/timer.wren` using `util/wren_to_c_string.py`
+
 static const char* timerModuleSource =
 "import \"scheduler\" for Scheduler\n"
 "\n"