fix: extraneous comma

Author: zpg6

src/lib.rs

@@ -45,7 +45,7 @@
 //!
 //! For writing files:
 //!
-//! ```rust,,ignore
+//! ```rust,ignore
 //! let my_other_file = root_dir.open_file_in_dir("MY_DATA.CSV", embedded_sdmmc::Mode::ReadWriteCreateOrAppend)?;
 //! my_other_file.write(b"Timestamp,Signal,Value\n")?;
 //! my_other_file.write(b"2025-01-01T00:00:00Z,TEMP,25.0\n")?;