Update runtime files.
diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index f20c706..f6cf2b5 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -1,4 +1,4 @@
-*index.txt* For Vim version 8.1. Last change: 2019 Jun 16
+*index.txt* For Vim version 8.1. Last change: 2019 Aug 16
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -1592,6 +1592,7 @@
|:spelldump| :spelld[ump] split window and fill with all correct words
|:spellgood| :spe[llgood] add good word for spelling
|:spellinfo| :spelli[nfo] show info about loaded spell files
+|:spellrare| :spellra[re] add rare word for spelling
|:spellrepall| :spellr[epall] replace all bad words like last |z=|
|:spellundo| :spellu[ndo] remove good or bad word
|:spellwrong| :spellw[rong] add spelling mistake