patch 8.1.1838: there is :spellwrong and :spellgood but not :spellrare

Problem:    There is :spellwrong and :spellgood but not :spellrare.
Solution:   Add :spellrare. (Martin Tournoij, closes #4291)
diff --git a/src/ex_cmdidxs.h b/src/ex_cmdidxs.h
index 1c301ba..c43e1f2 100644
--- a/src/ex_cmdidxs.h
+++ b/src/ex_cmdidxs.h
@@ -24,13 +24,13 @@
   /* q */ 358,
   /* r */ 361,
   /* s */ 381,
-  /* t */ 449,
-  /* u */ 494,
-  /* v */ 505,
-  /* w */ 523,
-  /* x */ 537,
-  /* y */ 547,
-  /* z */ 548
+  /* t */ 450,
+  /* u */ 495,
+  /* v */ 506,
+  /* w */ 524,
+  /* x */ 538,
+  /* y */ 548,
+  /* z */ 549
 };
 
 /*
@@ -59,7 +59,7 @@
   /* p */ {  1,  0,  3,  0,  4,  0,  0,  0,  0,  0,  0,  0,  0,  0,  7,  9,  0,  0, 16, 17, 26,  0, 27,  0, 28,  0 },
   /* q */ {  2,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 },
   /* r */ {  0,  0,  0,  0,  0,  0,  0,  0, 12,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 14, 19,  0,  0,  0,  0 },
-  /* s */ {  2,  6, 15,  0, 19, 23,  0, 25, 26,  0,  0, 29, 31, 35, 39, 41,  0, 49,  0, 50,  0, 62, 63,  0, 64,  0 },
+  /* s */ {  2,  6, 15,  0, 19, 23,  0, 25, 26,  0,  0, 29, 31, 35, 39, 41,  0, 50,  0, 51,  0, 63, 64,  0, 65,  0 },
   /* t */ {  2,  0, 19,  0, 24, 26,  0, 27,  0, 28,  0, 29, 33, 36, 38, 39,  0, 40, 42,  0, 43,  0,  0,  0,  0,  0 },
   /* u */ {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0, 10,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 },
   /* v */ {  0,  0,  0,  0,  1,  0,  0,  0,  4,  0,  0,  0,  9, 12,  0,  0,  0,  0, 15,  0, 16,  0,  0,  0,  0,  0 },
@@ -69,4 +69,4 @@
   /* z */ {  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0 }
 };
 
-static const int command_count = 561;
+static const int command_count = 562;