chore(cli): fix and improve help messages (#191)

A very small PR to fix an error in an help message, and improve the verbosity one.

Author: jeertmans

manim_slides/commons.py

@@ -57,7 +57,7 @@ def callback(ctx: Context, param: Parameter, value: bool) -> None:
             ["PERF", "DEBUG", "INFO", "WARNING", "ERROR", "CRITICAL"],
             case_sensitive=False,
         ),
-        help="Verbosity of CLI output",
+        help="Verbosity of CLI output. PERF will log performances (timing) information.",
         default=None,
         expose_value=False,
         envvar="MANIM_SLIDES_VERBOSITY",

manim_slides/present.py

@@ -906,7 +906,7 @@ def str_to_int_or_none(value: str) -> Optional[int]:
     "-s",
     "--skip-all",
     is_flag=True,
-    help="Skip all slides, useful the test if slides are working. Automatically sets `--skip-after-last-slide` to True.",
+    help="Skip all slides, useful the test if slides are working. Automatically sets `--exit-after-last-slide` to True.",
 )
 @click.option(
     "-r",