Suggestion to improve installation process

[ghost]

Hi! hope you're doing great. Here I'll suggest one change to the project.

Installation process

Currently, the installation process requires the execution of two commands, which are:

1. run curl to get the installation script and save in a install.sh file and
2. run the script with the installation directory location

Even thought it's simple, This process could be simplified with just one line command. Which would make the life of everyone easier.

Example

sh -c "$(curl -fsSL https://raw.githubusercontent.com/Shougo/dein.vim/master/bin/installer.sh)"

Of course, we would need to update the installation script.

I've been writing sh & bash for years and this simplification would be a nice feature to this wholesome project
If you don't have time, I can make one and open an PR just to give you an north about what I meant. Stay safe!

[Shougo]

Sorry. I don't want to change the example.
Yes, your script is simpler. But it is intended. User should check your installation script before the execution.

I will check your installation script later.