Read from SPIFFS and substitute multiple instances of data on server-side.
Row# HEADER 2 HEADER 3
%DATA1_1% %DATA1_2% %DATA1_3%
%DATA2_1% %DATA2_2% %DATA2_3%
%DATA3_1% %DATA3_2% %DATA3_3%
%DATA4_1% %DATA4_2% %DATA4_3%
%DATA5_1% %DATA5_2% %DATA5_3%
%DATA6_1% %DATA6_2% %DATA6_3%
%DATA7_1% %DATA7_2% %DATA7_3%
%DATA8_1% %DATA8_2% %DATA8_3%
%DATA9_1% %DATA9_2% %DATA9_3%
%DATA10_1% %DATA10_2% %DATA10_3%