Reword env var hint for dwarf debug info (#3081)

* Reword env var hint for dwarf debug info

Try not to declare that more information will indeed be displayed,
instead suggest that the output may improve if the env var is set since
dwarf debug info wasn't parsed.

cc bytecodealliance/wasmtime-go#90

* Fix test assertion

crates/wasmtime/src/trap.rs

@@ -363,7 +363,7 @@ impl fmt::Display for Trap {
             }
         }
         if self.inner.hint_wasm_backtrace_details_env {
-            writeln!(f, "note: run with `WASMTIME_BACKTRACE_DETAILS=1` environment variable to display more information")?;
+            writeln!(f, "note: using the `WASMTIME_BACKTRACE_DETAILS=1` environment variable to may show more debugging information")?;
         }
         Ok(())
     }