docs: improve explanation of the default.

Author: ldez

.golangci.example.yml

@@ -66,8 +66,8 @@ run:
 
   # Define the Go version limit.
   # Mainly related to generics support in go1.18.
-  # Default: 1.17
-  go: 1.18
+  # Default: use Go version from the go.mod file, fallback on the env var `GOVERSION`, fallback on 1.17
+  go: '1.18'
 
 
 # output configuration options