Update basis_spec.txt
diff --git a/spec/basis_spec.txt b/spec/basis_spec.txt
index 6f71594..3d06ba5 100644
--- a/spec/basis_spec.txt
+++ b/spec/basis_spec.txt
@@ -836,7 +836,7 @@
-----------------------------------------
ETC1S .basis files can have optional alpha channels, stored in odd slices. If any slice needs an alpha channel,
-all slices must have alpha channels. basis_file_header::m_flags will be logically OR's with
+all slices must have alpha channels. basis_file_header::m_flags will be logically OR'd with
cBASISHeaderFlagHasAlphaSlices. Alpha channel ETC1S files will contain two slices for each mipmap level
(or face, or video frame, etc.). The even slices will contain the RGB data, and the odd slices will contain
the alpha data, both stored in ETC1S format. A decoder can first decode the RGB data slice, then the next alpha
