docs: add ingest_cargo_file tool to README

Add the ingest_cargo_file tool to the Advanced Tools section, highlighting
its capability to bulk ingest dependencies from Cargo.toml/Cargo.lock files
with automatic version resolution.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: Peter

README.md

@@ -101,6 +101,7 @@ claude mcp add docsrs --env MAX_CACHE_SIZE_GB=5 -- uvx --from git+https://github
 | Tool | Description |
 |------|-------------|
 | `start_pre_ingestion` | Pre-load popular crates for instant access |
+| `ingest_cargo_file` | Bulk ingest dependencies from Cargo.toml/Cargo.lock with version resolution |
 | `list_versions` | List all available crate versions |
 
 ## Architecture