fix pandoc-wrapper.sh error code and ,gitignore sort comment

When `bin/pandoc-wrapper.sh` encounters a fatal error, it will
leave behind `debug.input.md` and `debug.output.html`.

Added `debug.input.md` and `debug.output.html` to `.gitignore`.

The `.gitignore` file comment noew refers to `sgi.sh` not sgi.

Changed `bin/pandoc-wrapper.sh` VERSION from "1.6.2 2024-04-18"
to 1.6.3 2024-06-22" to preform the above.

Perform `make www` to perform the above and test under macOS.

.gitignore

@@ -1,5 +1,5 @@
 #
-# sort with: bin/sgi
+# sort with: bin/sgi.sh
 .DS_Store
 /NOTES
 /archive/historic/1984
@@ -29,8 +29,9 @@
 /archive/historic/2018
 /archive/historic/2019
 /archive/historic/2020
-.tmp.*
+debug.input.md
+debug.output.html
 .su[a-z]
 .*.sv[a-z]
 .*.sw[a-z]
-.sw[a-z]
+.tmp.*