chore: refine README

Author: SSebo

README.md

@@ -1,10 +1,10 @@
 # FeatureProbe Server Side SDK for Rust
+
 [![Top Language](https://img.shields.io/github/languages/top/FeatureProbe/server-sdk-rust)](https://github.com/FeatureProbe/server-sdk-rust/search?l=rust)
 [![codecov](https://codecov.io/gh/featureprobe/server-sdk-rust/branch/main/graph/badge.svg?token=TAN3AU4CK2)](https://codecov.io/gh/featureprobe/server-sdk-rust)
 [![Github Star](https://img.shields.io/github/stars/FeatureProbe/server-sdk-rust)](https://github.com/FeatureProbe/server-sdk-rust/stargazers)
 [![Apache-2.0 license](https://img.shields.io/github/license/FeatureProbe/FeatureProbe)](https://github.com/FeatureProbe/FeatureProbe/blob/main/LICENSE)
 
-
 Feature Probe is an open source feature management service. This SDK is used to control features in rust programs. This
 SDK is designed primarily for use in multi-user systems such as web servers and applications.
 
@@ -33,7 +33,7 @@ After you install and import the SDK, create a single, shared instance of the Fe
 
 ```rust
 fn main() {
-    let remote_url = args.host_url + "/api/server/toggles";
+    let remote_url = "http://localhost:4007";
 
     let config = FPConfig {
         remote_url: remote_url.to_owned(),
@@ -56,7 +56,7 @@ fn main() {
 
 You can use sdk to check which variation a particular user will receive for a given feature flag.
 
-```
+```rust
 let user = FPUser::new("user@company.com").with("name", "bob");
 let show_feature = fp.bool_value("your.toggle.key", &user, false);
 
@@ -67,17 +67,7 @@ if show_feature {
 }
 ```
 
-## Testing for sdk
-
-We have unified integration tests for all our SDKs. Integration test cases are added as submodules for each SDK repo. So
-be sure to pull submodules first to get the latest integration tests before running tests.
-
-```shell
-git pull --recurse-submodules
-cargo test
-```
-
-## Testing for caller
+### Step 4. Unit Testing (Optional)
 
 You could do unit testing for each variation:
 
@@ -94,6 +84,16 @@ assert_eq!(fp.number_value("toggle_2", &u, 20.0), 12.5);
 assert_eq!(fp.string_value("toggle_3", &u, "val".to_owned()), "value");
 ```
 
+## Testing SDK
+
+We have unified integration tests for all our SDKs. Integration test cases are added as submodules for each SDK repo. So
+be sure to pull submodules first to get the latest integration tests before running tests.
+
+```shell
+git pull --recurse-submodules
+cargo test
+```
+
 ## Contributing
 
 We are working on continue evolving FeatureProbe core, making it flexible and easier to use.