feat: add callback function in config to get pdf currentpage and totalpage count

[VAJRESH]

Added config option to get pdf data

// only applicable for pdf getPdfData: ({ currentPage, totalPages }) => { console.log("pdf data", totalPages, currentPage); },

this config callback function is called when user changes the pdf page in horizontal scroll or scrolls down to change page in vertical scroll

Also updated readme file

[bulgemi]

I'm waiting... I hope it merges soon!