Better help logs

src/main.rs

···
 fn help() {
-    println!("\n\nHELP: tangled-on-commit\n\n")
+    println!("Help: tangled-on-commit
+Listen for commits on a specified repository and execute a shell command.
+
+CLI Arguments:
+    `tangled-on-commit (-h | --help)`
+            Displays this message
+
+    `tangled-on-commit`
+            No specified handle, repo, or command. Falls back to config/env
+
+    `tangled-on-commit SHELL`
+            Uses config/env for handle and repo
+
+    `tangled-on-commit @HANDLE SHELL`
+            Uses config/env for repo
+
+    `tangled-on-commit REPO SHELL`
+            Uses config/env for handle
+
+    `tangled-on-commit @HANDLE/REPO SHELL`
+    `tangled-on-commit HANDLE REPO SHELL`
+            No config/env
+
+JSON:
+    Loads the file `tangled-on-commit.json` from cwd if it exists.
+    Reads keys \"handle\", \"repo_name\", and \"shell\".
+    Unknown keys are ignored and any key can be ommitted
+    JSON is used if the arguments aren't passed to the CLI
+
+Env:
+    Loads the environment variables `TANGLED_ON_COMMIT_HANDLE` and `TANGLED_ON_COMMIT_REPO_NAME`
+    Shell cannot be set by environment variables.
+    Env variables are used if relevant keys are ommitted an arguments aren't passed to the CLI.
+")
 }
 
 #[derive(Debug)]
···
 
     // couldnt resolve every value
     // print an error and quit
-    println!("@{handle:?}/{repo_name:?}: {shell:?}");
+    println!("Unable to find a value for every setting. Missing values for:");
+    if handle.is_none() {println!("- handle");}
+    if repo_name.is_none() {println!("- repo_name");}
+    if shell.is_none() {println!("- shell");}
+    println!("\nRun `tangled-on-commit --help` to see the help message");
     return Err(());
 }