docs: Remove escaping '\' from literals

commit 35066ed6c6 replaced entities, but
escaped the replacement text also inside literals, which resulted in the
escaping '\' to also appear in the documentation.

https://bugzilla.gnome.org/show_bug.cgi?id=727320

glib/gdatetime.c

@@ -2548,7 +2548,7 @@ g_date_time_format_locale (GDateTime   *datetime,
  * - \%C: the century number (year/100) as a 2-digit integer (00-99)
  * - \%d: the day of the month as a decimal number (range 01 to 31)
  * - \%e: the day of the month as a decimal number (range  1 to 31)
- * - \%F: equivalent to `\%Y-\%m-\%d` (the ISO 8601 date format)
+ * - \%F: equivalent to `%Y-%m-%d` (the ISO 8601 date format)
  * - \%g: the last two digits of the ISO 8601 week-based year as a
  *   decimal number (00-99). This works well with \%V and \%u.
  * - \%G: the ISO 8601 week-based year as a decimal number. This works

glib/gkeyfile.c

@@ -116,7 +116,7 @@
  * Key-value pairs generally have the form `key=value`, with the
  * exception of localized strings, which have the form
  * `key[locale]=value`, with a locale identifier of the
- * form `lang_COUNTRY\@MODIFIER` where `COUNTRY` and `MODIFIER`
+ * form `lang_COUNTRY@MODIFIER` where `COUNTRY` and `MODIFIER`
  * are optional.
  * Space before and after the '=' character are ignored. Newline, tab,
  * carriage return and backslash characters in value are escaped as \n,

glib/grand.c

@@ -92,7 +92,7 @@
  *
  * The g_rand*_range functions will return high quality equally
  * distributed random numbers, whereas for example the
- * `(g_random_int()\%max)` approach often
+ * `(g_random_int()%max)` approach often
  * doesn't yield equally distributed numbers.
  *
  * GLib changed the seeding algorithm for the pseudo-random number