Fix kokoro lexicon. (#1886)

还钱 is mispronounced.

@@ -110,10 +110,15 @@ if [ ! -f ./tokens.txt ]; then
   ./generate_tokens.py
 fi
 
-if [ ! -f ./lexicon.txt ]; then
+if [ ! -f ./lexicon-zh.txt ]; then
   ./generate_lexicon.py
 fi
 
+grep '还钱' ./lexicon-zh.txt
+sed -i.bak 's/还钱 x a i/还钱 x w a/' ./lexicon-zh.txt
+rm -v ./lexicon-zh.txt.bak
+grep '还钱' ./lexicon-zh.txt
+
 if [ ! -f ./voices.bin ]; then
   ./generate_voices_bin.py
 fi