Register, update, and delete aliases

docs/source/users/index.md

@@ -548,3 +548,56 @@ As a shortcut for explaining errors, you can use the `%ai error` command, which
 %ai error anthropic:claude-v1.2
 ```
 
+### Creating and managing aliases
+
+You can create an alias for a model using the `%ai register` command. For example, the command:
+
+```
+%ai register claude anthropic:claude-v1.2
+```
+
+will register the alias `claude` as pointing to the `anthropic` provider's `claude-v1.2` model. You can then use this alias as you would use any other model name:
+
+```
+%%ai claude
+Write a poem about C++.
+```
+
+You can also define a custom LangChain chain:
+
+```
+from langchain.chains import LLMChain
+from langchain.prompts import PromptTemplate
+from langchain.llms import OpenAI
+
+llm = OpenAI(temperature=0.9)
+prompt = PromptTemplate(
+    input_variables=["product"],
+    template="What is a good name for a company that makes {product}?",
+)
+chain = LLMChain(llm=llm, prompt=prompt)
+```
+
+… and then use `%ai register` to give it a name:
+
+```
+%ai register companyname chain
+```
+
+You can change an alias's target using the `%ai update` command:
+
+```
+%ai update claude anthropic:claude-instant-v1.0
+```
+
+You can delete an alias using the `%ai delete` command:
+
+```
+%ai delete claude
+```
+
+You can see a list of all aliases by running the `%ai list` command.
+
+Aliases' names can contain ASCII letters (uppercase and lowercase), numbers, hyphens, underscores, and periods. They may not contain colons. They may also not override built-in commands — run `%ai help` for a list of these commands.
+
+Aliases must refer to models or `LLMChain` objects; they cannot refer to other aliases.