doc: put example above anything else in usage

README.md

@@ -12,8 +12,8 @@ gRoxy is a gRPC mocking server that allows you to mock gRPC services and respons
 
 - [installation](#installation)
 - [usage](#usage)
-  - [configuration](#configuration)
   - [example](#example)
+  - [configuration](#configuration)
   - [groxypb](#groxypb)
     - [nested messages](#nested-messages)
     - [enums](#enums)
@@ -53,6 +53,30 @@ Help Options:
   -h, --help                 Show this help message
 ```
 
+### example
+The simplest configuration for a method "Stub" would look like this:
+
+```yaml
+version: 1
+
+rules:
+  - match: { uri: "com.github.Semior001.groxy.example.mock.ExampleService/Stub" }
+    respond:
+      body: |
+        message StubResponse {
+            option              (groxypb.target) = true; // this option specifies that the message is a response 
+            string message = 1 [(groxypb.value)  = "Hello, World!"];
+            int32 code     = 2 [(groxypb.value)  = "200"];
+        }
+```
+
+That's it. You just need to define the response message, mark it as a target response message via the option, and set values via the value option. The response message will be sent to the client when the client calls the "Stub" method. No need for providing protosets, no need for providing the whole set of definitions, just the message you want to send.
+
+More importantly, if your response message contains lots of fields, which are not important for the test, you can just ignore them. gRoxy will leave them empty, and the client will not be able to distinguish between the real server and the mock server. That's ensured by the protobuf's backward compatibility.
+
+Field is backward compatible if it's of the same type and the same number. Names of the fields and messages are not important.
+
+
 ### configuration
 gRoxy uses a YAML configuration file to define the rules for the gRPC mocking server. The configuration file consists of the following sections:
 
@@ -154,26 +178,3 @@ message StubResponse {
     map<string, string> map_field = 1 [(groxypb.value) = '{"key1": "value1", "key2": "value2"}'];
 }
 ```
-
-## example
-The simplest configuration for a method "Stub" would look like this:
-
-```yaml
-version: 1
-
-rules:
-  - match: { uri: "com.github.Semior001.groxy.example.mock.ExampleService/Stub" }
-    respond:
-      body: |
-        message StubResponse {
-            option              (groxypb.target) = true; // this option specifies that the message is a response 
-            string message = 1 [(groxypb.value)  = "Hello, World!"];
-            int32 code     = 2 [(groxypb.value)  = "200"];
-        }
-```
-
-That's it. You just need to define the response message, mark it as a target response message via the option, and set values via the value option. The response message will be sent to the client when the client calls the "Stub" method. No need for providing protosets, no need for providing the whole set of definitions, just the message you want to send.
-
-More importantly, if your response message contains lots of fields, which are not important for the test, you can just ignore them. gRoxy will leave them empty, and the client will not be able to distinguish between the real server and the mock server. That's ensured by the protobuf's backward compatibility.
-
-Field is backward compatible if it's of the same type and the same number. Names of the fields and messages are not important.