Correct `bitsize` / `bytesize` comment.

PiperOrigin-RevId: 456036925
Change-Id: I062c462fa41624ed618e156b35ff8fd6f5cbc034
diff --git a/stg.h b/stg.h
index 46a4562..f0b29ea 100644
--- a/stg.h
+++ b/stg.h
@@ -358,7 +358,7 @@
   Encoding GetEncoding() const { return encoding_; }
 
   // GetBitSize() gives the semantics of the field. GetByteSize() gives the
-  // storage size, and is equal or greater than GetBitSize()*8
+  // storage size, and is equal to GetBitSize() / 8 rounded up.
   uint32_t GetBitSize() const { return bitsize_; }
   uint32_t GetByteSize() const { return bytesize_; }
   Name MakeDescription(const Graph& graph, NameCache& names) const final;