Fix typo at error -> panic

Author: Александр Кравцов

src/error/panic.md

@@ -1,7 +1,7 @@
 # `panic`
 
 The simplest error handling mechanism we will see is `panic`. It prints an 
-error message, starts unwinding the task, and usually exits the program. 
+error message, starts unwinding the stack, and usually exits the program. 
 Here, we explicitly call `panic` on our error condition: 
 
 ```rust,editable,ignore,mdbook-runnable