Fix common misspellings
I stumbled upon the typo in README.draft, so took the opportunity to
grep for common misspellings using List_of_common_misspellings.txt for
hunspell.
diff --git a/include/opus.h b/include/opus.h
index 2add784..cdd9677 100644
--- a/include/opus.h
+++ b/include/opus.h
@@ -371,7 +371,7 @@
* @li max_size is the max duration of the frame in samples (per channel) that can fit into the decoded_frame array
*
* opus_decode() and opus_decode_float() return the number of samples (per channel) decoded from the packet.
- * If that value is negative, then an error has occured. This can occur if the packet is corrupted or if the audio
+ * If that value is negative, then an error has occurred. This can occur if the packet is corrupted or if the audio
* buffer is too small to hold the decoded audio.
*
* Opus is a stateful codec with overlapping blocks and as a result Opus
diff --git a/include/opus_multistream.h b/include/opus_multistream.h
index 9ae1711..2bf1dff 100644
--- a/include/opus_multistream.h
+++ b/include/opus_multistream.h
@@ -108,7 +108,7 @@
* elementary Opus stream, the encoder and decoder must negotiate the channel
* configuration before the decoder can successfully interpret the data in the
* packets produced by the encoder. Some basic information, such as packet
- * duration, can be computed without any special negotation.
+ * duration, can be computed without any special negotiation.
*
* The format for multistream Opus packets is defined in the
* <a href="http://tools.ietf.org/html/draft-terriberry-oggopus">Ogg