Add -h option

README.md

@@ -5,4 +5,6 @@
 ```sh
 $ make install
 $ flytex2html main.tex > out.html
+
+$ flytex2html --help
 ```

src/flytex2html.py

@@ -22,6 +22,10 @@ def main() -> None:
     arguments = sys.argv.copy()
     arguments.pop(0)  # remove script name
 
+    if "-h" in arguments or "--help" in arguments:
+        usage()
+        sys.exit(1)
+
     # Handle flags that don't come in pairs
     if "-v" in arguments or "--verbose" in arguments:
         try:
@@ -80,6 +84,8 @@ def usage() -> None:
     {executable} FILE [--origin-paths] [{{-t|--title}} TITLE] [{{-v|--verbose}}]
 
     Options:
+        -h, --help
+            Print this help message and exit.
         --origin-paths
             Keep the paths in the input file as they are.
             This means you will probably need to copy the images over to destination.