chore: example and readme

README.md

@@ -3,6 +3,11 @@
 
 Config `Cargo.toml`:
 ```
+[dependencies]
+rust_util = "0.6"
+
+--OR--
+
 [dependencies]
 rust_util = { git = "https://github.com/jht5945/rust_util" }
 ```
@@ -27,9 +32,20 @@ Run example:
 $ cargo run --example log
 ```
 
+<br>
+
+ENV `LOGGER_LEVEL` can be:
+- `debug` or `*`
+- `info` or `?` -- default
+- `ok` or `#`
+- `warn` or `!`
+- `error` or `^`
+
 
 ## Update Log
 
+* Nov 28, 2020 v0.6.19
+    * add util_git
 * Nov 28, 2020 v0.6.18
     * add util_term
 * Jun 21, 2020 v0.3.0