Add ttyper completions (#928)

Added ttyper completions. Ttyper is a little tool for speed typists
(readme included).

custom-completions/ttyper/README.md

@@ -0,0 +1,3 @@
+# ttyper
+
+[ttyper](https://github.com/max-niederman/ttyper) is a terminal-based typing test built with Rust and Ratatui.

custom-completions/ttyper/ttyper-completions.nu

@@ -0,0 +1,18 @@
+# author: David Telenko
+
+def "nu-complete languages" [] {
+  ttyper --list-languages | lines
+}
+
+export extern "ttyper" [
+     --debug(-d)
+     --help(-h)                        # Prints help information
+     --list-languages                  # List installed languages
+     --no-backtrack                    # Disable backtracking to completed words
+     --sudden-death                    # Enable sudden death mode to restart on first error
+     --version(-V)                     # Prints version information
+     --config(-c): path                # Use config file
+     --language(-l): string@"nu-complete languages" # Specify test language
+     --language-file                   # Specify test language in file
+     --words(-w): int                  # Specify word count [default: 50]
+]