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/runtime/doc/spell.txt b/runtime/doc/spell.txt
index 4a28cdc..ff6feb6 100644
--- a/runtime/doc/spell.txt
+++ b/runtime/doc/spell.txt
@@ -121,6 +121,23 @@
:spellw[rong]! {word} Add {word} as a wrong (bad) word to the internal word
list, like with |zW|.
+ *:spellr* *:spellrare*
+:[count]spellr[are] {word}
+ Add {word} as a rare word to 'spellfile', similar to
+ |zw|. Without count the first name is used, with
+ a count of two the second entry, etc.
+
+ There are no normal mode commands to mark words as
+ rare as this is a fairly uncommon command and all
+ intuitive commands for this are already taken. If you
+ want you can add mappings with e.g.: >
+ nnoremap z? :exe ':spellrare ' . expand('<cWORD>')<CR>
+ nnoremap z/ :exe ':spellrare! ' . expand('<cWORD>')<CR>
+< |:spellundo|, |zuw|, or |zuW| can be used to undo this.
+
+:spellr[rare]! {word} Add {word} as a rare word to the internal word
+ list, similar to |zW|.
+
:[count]spellu[ndo] {word} *:spellu* *:spellundo*
Like |zuw|. [count] used as with |:spellgood|.