Document synchronous stubs (#82)

* Document synchronous clients

* Remove outdated migrating page

Author: AdrienVannson

docs/migrating.md

@@ -0,0 +1,44 @@
+# Clients
+
+!!! warning
+    Make sure to enable client generation when compiling your code. See [TODO link]
+
+## Synchronous clients
+
+Compile the following proto file in a directory called `example`, with the generation of synchronous clients activated.
+
+```proto
+syntax = "proto3";
+
+message Request {}
+message Response {}
+
+service MyService {
+    rpc MyRPC(Request) returns (Response);
+}
+```
+
+The synchronous client can be used as follows:
+
+```python
+import grpc
+
+from example import Request, MyServiceStub
+
+with grpc.insecure_channel("address:port") as channel:
+    client = MyServiceStub(channel)
+
+    response = client.my_rpc(Request())
+```
+
+## Asynchronous clients
+
+### With grpcio
+
+!!! warning
+    No yet supported
+
+### With grpclib
+
+!!! warning
+    Documentation not yet available

docs/tutorial/clients.md

@@ -15,8 +15,8 @@ nav:
      - Getting Started: getting-started.md
      - Tutorial:
         - Messages: tutorial/messages.md
+        - Clients: tutorial/clients.md
      - API: api.md
-     - Migrating: migrating.md
   - Betterproto2 compiler: https://betterproto.github.io/python-betterproto2-compiler/
 
 plugins: