Changelog, fix typos

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
diff --git a/Changelog b/Changelog
index e82ae69..4b1edd2 100644
--- a/Changelog
+++ b/Changelog
@@ -7,7 +7,7 @@
 - bink: check vst->index_entries before using it
 - mpeg4videodec: only allow a positive length
 - alsdec: check sample pointer range in revert_channel_correlation
-- avcodec/h264_refs: Do not set reference to things which dont exist
+- avcodec/h264_refs: Do not set reference to things which do not exist
 - avcodec/h264: Fail for invalid mixed IDR / non IDR frames in slice threading mode
 - h264: avoid unnecessary calls to get_format
 - avutil/pca: Check for av_malloc* failures
@@ -29,7 +29,7 @@
 - avcodec/h264: Be more tolerant to changing pps id between slices
 - avcodec/aacdec: Fix storing state before PCE decode
 - avcodec/h264: reset the counts in the correct context
-- avcodec/h264_slice: Dont reset mb_aff_frame per slice
+- avcodec/h264_slice: Do not reset mb_aff_frame per slice
 - tests: Fix test name for pixfmts tests
 - avcodec/h264: finish previous slices before switching to single thread mode
 - avcodec/h264: Fix race between slices where one overwrites data from the next