fix(publisher-s3): typo makes argument not match the variable name (#194

)

config/publishers/s3.md

@@ -59,7 +59,7 @@ To avoid this problem, you can use the `keyResolver` option to generate the S3 k
   name: '@electron-forge/publisher-s3',
   config: {
     // ...
-    keyResolver: (fileName, platform, arch) => {
+    keyResolver: (filename, platform, arch) => {
       return `some-prefix/${platform}/${arch}/${filename}`
     }
     // ...