Update: make config.toml path platform-aware in docs (#460)

Docs hardcoded the Linux `~/.config/fledge/config.toml` path, but the
code resolves via `dirs::config_dir()` (macOS `~/Library/Application
Support/fledge/`, Windows `%APPDATA%\fledge\`, Linux `~/.config/fledge/`).

Clarify the most prominent occurrences using SECURITY.md's File Locations
wording:
- cli-reference.md `fledge config` section: full platform mapping plus a
  pointer to `fledge config path` and the Configuration page
- cli-reference.md `ai use`: no longer hardcodes the Linux path
- doctor.md `fledge config` check: brief platform-aware note

The canonical Configuration and Plugins pages already carry the full
platform table; passing cross-references and code-block comments are left
as-is.


Claude-Session: https://claude.ai/code/session_016AvsKakjAc3EKN2ztcMfYi

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Author: 0xLeif

site/src/content/docs/reference/cli-reference.md

@@ -345,7 +345,7 @@ fledge ai <status|models|use> [OPTIONS]
 
 - `status [--json]`: Show active provider, model, and host with a `(from env / config / default)` source tag on each value
 - `models --provider {ollama,anthropic,openai,...} [--search <q>] [--json]`: Model list (Ollama hits `/api/tags`; Anthropic returns curated ids; OpenAI-compatible gateways aren't enumerable)
-- `use [provider] [model]`: Interactive picker (live model list for Ollama) or fully scriptable via positional args. Writes to `~/.config/fledge/config.toml`
+- `use [provider] [model]`: Interactive picker (live model list for Ollama) or fully scriptable via positional args. Writes to the global `config.toml` (platform config dir; see [Configuration](./configuration.md))
 
 ```bash
 fledge ai status                                  # who's active and why
@@ -677,7 +677,11 @@ fledge plugins audit --json                             # machine-readable audit
 
 ### fledge config `<action>`
 
-Manage `~/.config/fledge/config.toml`.
+Manage the global `config.toml`. Its location follows the platform config
+directory (`dirs::config_dir()`): `~/Library/Application Support/fledge/config.toml`
+on macOS, `~/.config/fledge/config.toml` on Linux, `%APPDATA%\fledge\config.toml`
+on Windows. Run `fledge config path` to print the resolved location, or see
+[Configuration](./configuration.md).
 
 ```text
 fledge config <get|set|unset|add|remove|edit|list|path|init>

site/src/content/docs/reference/doctor.md

@@ -20,7 +20,7 @@ Doctor reports four sections:
 
 ### `fledge`
 
-- `fledge config`. Does `~/.config/fledge/config.toml` parse cleanly?
+- `fledge config`. Does the global `config.toml` parse cleanly? (Its path follows the platform config dir; see [Configuration](./configuration.md).)
 
 ### `Git`