docs(readme): remove old migration guide (#289)

README.md

@@ -8,70 +8,6 @@ and offers both synchronous and asynchronous clients powered by [httpx](https://
 
 For the AWS Bedrock API, see [`anthropic-bedrock`](https://github.com/anthropics/anthropic-bedrock-python).
 
-## Migration from v0.2.x and below
-
-In `v0.3.0`, we introduced a fully rewritten SDK.
-
-The new version uses separate sync and async clients, unified streaming, typed params and structured response objects, and resource-oriented methods:
-
-**Sync before/after:**
-
-```diff
-- client = anthropic.Client(os.environ["ANTHROPIC_API_KEY"])
-+ client = anthropic.Anthropic(api_key=os.environ["ANTHROPIC_API_KEY"])
-  # or, simply provide an ANTHROPIC_API_KEY environment variable:
-+ client = anthropic.Anthropic()
-
-- rsp = client.completion(**params)
-- rsp["completion"]
-+ rsp = client.completions.create(**params)
-+ rsp.completion
-```
-
-**Async before/after:**
-
-```diff
-- client = anthropic.Client(os.environ["ANTHROPIC_API_KEY"])
-+ client = anthropic.AsyncAnthropic(api_key=os.environ["ANTHROPIC_API_KEY"])
-
-- await client.acompletion(**params)
-+ await client.completions.create(**params)
-```
-
-The `.completion_stream()` and `.acompletion_stream()` methods have been removed;
-simply pass `stream=True`to `.completions.create()`.
-
-Streaming responses are now incremental; the full text is not sent in each message,
-as v0.3 sends the `Anthropic-Version: 2023-06-01` header.
-
-<details>
-<summary>Example streaming diff</summary>
-
-```diff py
-  import anthropic
-
-- client = anthropic.Client(os.environ["ANTHROPIC_API_KEY"])
-+ client = anthropic.Anthropic()
-
-  # Streams are now incremental diffs of text
-  # rather than sending the whole message every time:
-  text = "
-- stream = client.completion_stream(**params)
-- for data in stream:
--     diff = data["completion"].replace(text, "")
--     text = data["completion"]
-+ stream = client.completions.create(**params, stream=True)
-+ for data in stream:
-+     diff = data.completion # incremental text
-+     text += data.completion
-      print(diff, end="")
-
-  print("Done. Final text is:")
-  print(text)
-```
-
-</details>
-
 ## Documentation
 
 The API documentation can be found [here](https://docs.anthropic.com/claude/reference/).