docs(i2s): Fix I2S documentation example

Author: lucasssvaz

Diff for: docs/en/api/i2s.rst

@@ -536,21 +536,21 @@ Sample code
   #include <ESP_I2S.h>
 
   const int buff_size = 128;
-  int available, read;
+  int available_bytes, read_bytes;
   uint8_t buffer[buff_size];
   I2SClass I2S;
 
   void setup() {
     I2S.setPins(5, 25, 26, 35, 0); //SCK, WS, SDOUT, SDIN, MCLK
     I2S.begin(I2S_MODE_STD, 16000, I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_STEREO);
     I2S.read();
-    available = I2S.available();
-    if(available < buff_size) {
-      read = I2S.read(buffer, available);
+    available_bytes = I2S.available();
+    if(available_bytes < buff_size) {
+      read_bytes = I2S.read(buffer, available_bytes);
     } else {
-      read = I2S.read(buffer, buff_size);
+      read_bytes = I2S.read(buffer, buff_size);
     }
-    I2S.write(buffer, read);
+    I2S.write(buffer, read_bytes);
     I2S.end();
   }