Fix README.md grammar "e.g.,"

A punctuation mark always precedes e.g. In American English a comma
should follow e.g. The list of examples following e.g. should not be
exhaustive.

Reference: https://en.wiktionary.org/wiki/e.g.

1 files changed, 1 insertions, 1 deletions

diff --git a/README.md b/README.md
index 22fd9ea..c6b5caf 100644
--- a/README.md
+++ b/README.md
@@ -37,7 +37,7 @@ however, client-side configuration for max size, the `data-max-size` attribute
 on the file input in `pages/upload_form.swig`.
 
 Make sure to disable PHP from being executed on the file download
-domain/directory (e.g `a.pomf.example`), otherwise an attacker can upload a
+domain/directory (e.g., `a.pomf.example`), otherwise an attacker can upload a
 malicious `.php` file and execute it on your server.
 
 ### Apache