doc: Fix best_nb_channells typo

Signed-off-by: Peter Meerwald <p.meerwald@bct-electronic.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/api-example.c

@@ -82,7 +82,7 @@ static int select_channel_layout(AVCodec *codec)
 {
     const uint64_t *p;
     uint64_t best_ch_layout = 0;
-    int best_nb_channells   = 0;
+    int best_nb_channels   = 0;
 
     if (!codec->channel_layouts)
         return AV_CH_LAYOUT_STEREO;
@@ -91,9 +91,9 @@ static int select_channel_layout(AVCodec *codec)
     while (*p) {
         int nb_channels = av_get_channel_layout_nb_channels(*p);
 
-        if (nb_channels > best_nb_channells) {
+        if (nb_channels > best_nb_channels) {
             best_ch_layout    = *p;
-            best_nb_channells = nb_channels;
+            best_nb_channels = nb_channels;
         }
         p++;
     }