_content/ref/mod: fix typo

Change-Id: I5581e2e62ab449826cc6086cd1948fdd7021563f
GitHub-Last-Rev: f1e468fb0c1cebd889b42ee83d7b393089f978c7
GitHub-Pull-Request: golang/website#99
Reviewed-on: https://go-review.googlesource.com/c/website/+/355030
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Trust: Daniel Martí <mvdan@mvdan.cc>
Trust: Alberto Donizetti <alb.donizetti@gmail.com>
diff --git a/_content/ref/mod.md b/_content/ref/mod.md
index 04d22ad..c3429a1 100644
--- a/_content/ref/mod.md
+++ b/_content/ref/mod.md
@@ -2914,7 +2914,7 @@
 This special case allows the same `LICENSE` file to apply to all modules within
 a repository. This only applies to files named `LICENSE` specifically, without
 extensions like `.txt`. Unfortunately, this cannot be extended without breaking
-cryptographic sums of exesting modules; see [Authenticating
+cryptographic sums of existing modules; see [Authenticating
 modules](#authenticating). Other tools and websites like
 [pkg.go.dev](https://pkg.go.dev) may recognize files with other names.