Update README.md

Author: Andrey Safonov

README.md

@@ -19,4 +19,35 @@ The endpoint returns all files present in the files directory in JSON format.
 ##### HTTP Request
 `GET http://localhost:9000/files`
 
+#### Get file
+
+The endpoint returns the requested file.
+
+##### HTTP Request
+`GET http://localhost:9000/files/:filename`
+
+#### Get thumbnail
+
+The endpoint returns the thumbnail for the specified file. Uses [PDFTron Node.js API](https://www.pdftron.com/documentation/samples/node/js/PDFDrawTest?platforms=nodejs).
+
+##### HTTP Request
+`GET http://localhost:9000/thumbnail/:filename`
+
+#### Convert to PDF
+
+The endpoint converts the file to a PDF. Conversion is possible for the following file formats: DOC, DOCX, PPTX, PPT, XLSX, PNG, JPEG, JPG, TIFF, TXT. Uses [PDFTron Node.js API](https://www.pdftron.com/documentation/samples/node/js/ConvertTest?platforms=nodejs).
+
+##### HTTP Request
+`GET http://localhost:9000/convert/:filename`
+
+#### Optimize to PDF
+
+The endpoint converts the PDF to an optimized PDF to be used with [PDFTron WebViewer](https://www.pdftron.com/webviewer/demo/). Uses [PDFTron Node.js API](https://www.pdftron.com/api/pdfnet-node/PDFNet.PDFDoc.html#saveViewerOptimized__anchor).
+
+##### HTTP Request
+`GET http://localhost:9000/convert/:filename`
+
+
+
+