fix: remove incorrect resources claim from filesystem server README

The filesystem server does not actually implement MCP Resources capability
but the README incorrectly claimed it provides 'file://system' resource interface.

Fixes #399

Co-authored-by: Ola Hungerford <olaservo@users.noreply.github.com>

Author: claude[bot]

src/filesystem/README.md

@@ -64,10 +64,6 @@ The server's directory access control follows this flow:
 
 ## API
 
-### Resources
-
-- `file://system`: File system operations interface
-
 ### Tools
 
 - **read_text_file**