Update README.md

Author: simontime

README.md

@@ -2,8 +2,9 @@
 A utility for performing simple operations on stereo DSF files **without** re-encoding or conversion.
 
 Operations:
-- **swap**: Swaps left and right channel data
+- **swapch**: Swaps left and right channel data
 - **lisolate**: Isolates left channel; copies data to right channel
 - **risolate**: Isolates right channel; copies data to left channel
 - **linvert**: Inverts left channel phase
 - **rinvert**: Inverts right channel phase
+- **invert**: Inverts left and right channel phase