complementary code comments

on variables used / impacted during maxDist check

lib/compress/zstd_compress_internal.h

@@ -134,9 +134,9 @@ typedef struct {
 typedef struct ZSTD_matchState_t ZSTD_matchState_t;
 struct ZSTD_matchState_t {
     ZSTD_window_t window;   /* State for window round buffer management */
-    U32 loadedDictEnd;      /* index of end of dictionary, within dictionary's referential. Only used for attached dictionaries. Effectively same value as dictSize, since dictionary indexes start a zero */
+    U32 loadedDictEnd;      /* index of end of dictionary, within context's referential. When dict referential is copied into active context (i.e. not attached), effectively same value as dictSize, since referential starts at zero */
     U32 nextToUpdate;       /* index from which to continue table update */
-    U32 nextToUpdate3;      /* index from which to continue table update */
+    U32 nextToUpdate3;      /* index from which to continue table update of hashTable3 */
     U32 hashLog3;           /* dispatch table : larger == faster, more memory */
     U32* hashTable;
     U32* hashTable3;