Fix code block issues

api.rst

@@ -878,7 +878,7 @@ How is a text marked for translation
 
      ::
 
-        snprintf(buf, sizeof(buf), SANE_I18N("Start scan")
+        snprintf(buf, sizeof(buf), SANE_I18N("Start scan"));
 
    or
 
@@ -930,7 +930,7 @@ File formats and translation functions
 
      ::
 
-        snprintf(buf, sizeof(buf), gettext("english text"));
+        snprintf(buf, sizeof(buf), gettext("English text"));
 
    If a frontend author decides to use translation functions that need
    different translation tables, then the frontend is responsible to
@@ -2269,7 +2269,7 @@ Gamma Table Options
    scanner internal bit depth to the output bit depth. This should
    e.g. look like this:
 
-     ::
+     .. code-block:: none
 
         red_value   = gamma-table(red-gamma-table(value))
         green_value = gamma-table(green-gamma-table(value))