fix(acroforms): pdf path in acroforms example

[roiLeo]

Summary

f1040.pdf not found

Steps to reproduce

build acroforms example

Relevant logs

11:16:39,647 Uncaught (in promise) 
Object { message: "Missing PDF \"http://localhost:8888/test/pdfs/f1040.pdf\".", name: "MissingPDFException", stack: "BaseExceptionClosure@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:1296:29\n__webpack_modules__<@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:1299:2\n__w_pdfjs_require__@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:15195:41\n__webpack_modules__<@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:302:32\n__w_pdfjs_require__@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:15195:41\n__webpack_modules__<@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:237:41\n__w_pdfjs_require__@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:15195:41\n@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:15205:18\n@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:15206:12\nwebpackUniversalModuleDefinition@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:31:50\n@http://localhost:8888/node_modules/pdfjs-dist/build/pdf.js:32:3\n" }

[timvandermeij]

Thanks!