[gnome-software] lib: Add a comment for translators

[Piotr Drąg <piotrdrag src gnome org>]

commit 71b6476a4827bf45be3e3eedd6b29b8133214e8e
Author: Piotr Drąg <piotrdrag gmail com>
Date:   Mon Dec 4 19:30:26 2017 +0100

    lib: Add a comment for translators
    
    Explaining how you can switch the currency order
    to your locale’s convention.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=786704

 lib/gs-price.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/lib/gs-price.c b/lib/gs-price.c
index 698d897..a0589b2 100644
--- a/lib/gs-price.c
+++ b/lib/gs-price.c
@@ -126,6 +126,8 @@ gs_price_to_string (GsPrice *price)
        } else if (g_strcmp0 (price->currency, "USD") == 0) {
                return g_strdup_printf (_("US$%.2f"), price->amount);
        } else {
+               /* Translators: %s is the currency, and %f is the amount.
+                * You can switch the order by using “%2$f %1$s” instead. */
                return g_strdup_printf (_("%s %f"), price->currency, price->amount);
        }
 }