In computing, an typically refers to a fix applied to a database or file directory to correct errors in how data is located or retrieved. If you are seeing this specific phrase in a file directory (often referred to as an "Index of/"), it usually indicates that the directory has been modified or "patched" to allow or restrict access to the files within.
The term is derived from the 2013 biographical sports drama Bhaag Milkha Bhaag (Run Milkha Run), based on the life of Indian sprinter Milkha Singh. The film’s title is a motivational command to run fast and overcome obstacles. bhag milkha bhaag index patched