Fix typos in documentation comments

[yeaseul-kim]

Background

A spellcheck pass over lib/ turned up 19 misspellings in YARD documentation
comments, plus one in the opening comment of .rubocop.yml. Several are
repeats of the same word (truethy x4, formated x2, outputed x2), so they
show up in the generated docs in a few different places.

Change

Location	Before	After
lib/highline.rb:104	outputed	outputted
lib/highline.rb:108	indentated	indented
lib/highline.rb:134	truethy	truthy
lib/highline.rb:289	beind used in	being used in
lib/highline/list.rb:126	outputed	outputted
lib/highline/question.rb:372	succesful	successful
lib/highline/question.rb:593	truethy	truthy
lib/highline/question.rb:596	truethy	truthy
lib/highline/question.rb:599	truethy	truthy
lib/highline/statement.rb:34	formated	formatted
lib/highline/statement.rb:37	formated	formatted
lib/highline/style.rb:29	creted	created
lib/highline/style.rb:101	convertion	conversion
lib/highline/template_renderer.rb:56	contants	constants
lib/highline/terminal.rb:17	decend	descend
lib/highline/terminal.rb:64	Yieds	Yields
lib/highline/terminal.rb:80	accordling	accordingly
lib/highline/terminal.rb:143	@!group Enviroment queries	@!group Environment queries
lib/highline/terminal.rb:162	debuggin	debugging
.rubocop.yml:1	Bellow the changes	Below the changes

outputed is corrected to outputted rather than to the uninflected
output. Both are valid past participles, but outputted keeps the edit to
the misspelling itself instead of also changing the style, and it avoids the
brief noun/verb ambiguity in "suitable to be directly output to the screen".
Happy to use output instead if you prefer that form.

Scope

Comments only. No code, API or behaviour changes, so no tests are added.

Two things were deliberately left alone:

• Changelog.md has a handful of typos too (enviroment, begining,
  dependancy, implemetation, overides), but those are historical release
  notes, so editing them retroactively felt wrong.
• stringfy / stringfied / stringfies / stringfying are not typos in
  context — stringfy is a real method (lib/highline/list.rb:173,
  lib/highline/statement.rb:54) and the comments correctly refer to it.
  Renaming the method would be a breaking change, so both were left as is.

[abinoam]

Thank a lot for the PR! 👏