Comment enhancements.  Add an ALWAYS macro in fkey.c to indicate a branch
that is always taken.

FossilOrigin-Name: d5b714cffffe588dd4dd10e0b82df8d99657be88
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 4090c1a..cbf7cd5 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1283,9 +1283,9 @@
 ** the from-table is created.  The existence of the to-table is not checked.
 */
 struct FKey {
-  Table *pFrom;     /* The table that contains the REFERENCES clause */
+  Table *pFrom;     /* Table containing the REFERENCES clause (aka: Child) */
   FKey *pNextFrom;  /* Next foreign key in pFrom */
-  char *zTo;        /* Name of table that the key points to */
+  char *zTo;        /* Name of table that the key points to (aka: Parent) */
   FKey *pNextTo;    /* Next foreign key on table named zTo */
   FKey *pPrevTo;    /* Previous foreign key on table named zTo */
   int nCol;         /* Number of columns in this key */