Revert "docs: add reference to docs.ollama.com (#12800)" (#12803)

This reverts commit 934dd9e196.

docs/api/authentication.mdx

@@ -1,63 +0,0 @@
----
-title: Authentication
----
-
-No authentication is required when accessing Ollama's API locally via `http://localhost:11434`.
-
-Authentication is required for the following:
-
-* Running cloud models via ollama.com
-* Publishing models
-* Downloading private models
-
-Ollama supports two authentication methods:
-
-* **Signing in**: sign in from your local installation, and Ollama will automatically take care of authenticating requests to ollama.com when running commands
-* **API keys**: API keys for programmatic access to ollama.com's API
-
-## Signing in
-
-To sign in to ollama.com from your local installation of Ollama, run:
-
-```
-ollama signin
-```
-
-Once signed in, Ollama will automatically authenticate commands as required:
-
-```
-ollama run gpt-oss:120b-cloud
-```
-
-Similarly, when accessing a local API endpoint that requires cloud access, Ollama will automatically authenticate the request:
-
-```shell
-curl http://localhost:11434/api/generate -d '{
-  "model": "gpt-oss:120b-cloud",
-  "prompt": "Why is the sky blue?"
-}'
-```
-
-## API keys
-
-For direct access to ollama.com's API served at `https://ollama.com/api`, authentication via API keys is required.
-
-First, create an [API key](https://ollama.com/settings/keys), then set the `OLLAMA_API_KEY` environment variable:
-
-```shell
-export OLLAMA_API_KEY=your_api_key
-```
-
-Then use the API key in the Authorization header:
-
-```shell
-curl https://ollama.com/api/generate \
-  -H "Authorization: Bearer $OLLAMA_API_KEY" \
-  -d '{
-    "model": "gpt-oss:120b",
-    "prompt": "Why is the sky blue?",
-    "stream": false
-  }'
-```
-
-API keys don't currently expire, however you can revoke them at any time in your [API keys settings](https://ollama.com/settings/keys).