add completion for toipe (nushell#508)

Author: amtoine

custom-completions/toipe/toipe-completions.nu

@@ -0,0 +1,20 @@
+def "nu-complete toipe wordlists" [] {[
+    top250
+    top500
+    top1000
+    top2500
+    top5000
+    top10000
+    top25000
+    commonly-misspelled
+    os
+]}
+
+# external completion for toipe 0.4.1
+export extern toipe [
+    --file (-f): path  # Path to custom word list file. Providing this will override `-w`/`--wordlist`.
+    --help (-h)  # Print help information
+    --num-words (-n): int  # Number of words to show on each test [default: 30]
+    --version (-V)  # Print version information
+    --wordlist (-w): string@"nu-complete toipe wordlists" # Word list name [default: top250]
+]