Update README.md

Author: oclyke

README.md

@@ -29,12 +29,15 @@ The basic necesseties are in-place. This means that you can compile and upload c
   * Analog / Servo Output: ✅
   * Analog Input: ✅
   * Timing / Delays: ✅
+
+**Standard Libraries**
   * Wire
     * Master: ✅
     * Slave: ❌
   * SPI
     * Master: ✅
     * Slave: ❌
+  * Software Serial: ✅
 
 **Apollo3 Specialty Peripherals**
   * PDM Microphones / I2S: 🤔