Update the argument help messages

Author: bbhtt

README.md

@@ -44,14 +44,14 @@ git evtag --compat --sign TAG
 $ git evtag -h
 usage: git-evtag [-h] [--rev REV] [--repo REPO] [--verify VERIFY] [--sign SIGN] [--compat]
 
-Tree checksum of a git repository
+EVTag checksum of a git repository
 
 options:
   -h, --help       show this help message and exit
   --rev REV        Git revision (default: HEAD)
-  --repo REPO      Path to the git repository (default: current dir)
-  --verify VERIFY  Verify the tree checksum from the input tag message
-  --sign SIGN      Sign the input tag with the tree checksum
+  --repo REPO      Path to the git repository (default: PWD)
+  --verify VERIFY  Verify the EVTag checksum of the input tag
+  --sign SIGN      Sign the input tag with the EVTag checksum
   --compat         Produce 'Git-EVTag-v0-SHA512' prefixed output
 ```
 

git_evtag_py.py

@@ -366,15 +366,13 @@ def validate_args(args: argparse.Namespace) -> bool:
 
 
 def parse_args() -> argparse.Namespace:
-    parser = argparse.ArgumentParser(description="Tree checksum of a git repository")
+    parser = argparse.ArgumentParser(description="EVTag checksum of a git repository")
     parser.add_argument("--rev", help="Git revision (default: HEAD)")
     parser.add_argument(
-        "--repo", default=".", help="Path to the git repository (default: current dir)"
+        "--repo", default=".", help="Path to the git repository (default: PWD)"
     )
-    parser.add_argument(
-        "--verify", help="Verify the tree checksum from the input tag message"
-    )
-    parser.add_argument("--sign", help="Sign the input tag with the tree checksum")
+    parser.add_argument("--verify", help="Verify the EVTag checksum of the input tag")
+    parser.add_argument("--sign", help="Sign the input tag with the EVTag checksum")
     parser.add_argument(
         "--compat",
         action="store_true",