update README.md

create README.md

upload files in /demo

Запрос на слияние 'work-branch' (#3) из work-branch в master

update dev/solution.cs

update dev/solution.cs

create dev/solution.cs

create codex.md

update dev/solution.cs

create dev/solution.cs

delete dev/solution.cs

create dev/solution.cs

create codex.md