[Doc] Add current version on the top of README

[PeterDaveHello]

No description provided.

[ljharb]

This adds release overhead, or the risk it will go out of date.

Can you verify that make release will update this?

[PeterDaveHello]

Yes of course 👍 It'll update this part 😄

[ljharb]

Just want to be very explicit - you have actually ran make release manually and verified that it does update it?

[PeterDaveHello]

Correct:

$ make TAG=0.123.1 release 
=== Bumping version **0.32.1** to **0.123.1** before committing and tagging:
=== TYPE 'proceed' TO PROCEED, anything else to abort: proceed
nvm.sh
 3131:       nvm_echo '0.123.1'
install.sh
 14:   echo "v0.123.1"
README.markdown
 1: # Node Version Manager [![Build Status](https://travis-ci.org/creationix/nvm.svg?branch=master)][3] [![nvm version](https://img.shields.io/badge/version-v0.123.1-yellow.svg)]
 64: curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.123.1/install.sh | bash
 70: wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.123.1/install.sh | bash
 438: wget -qO- https://raw.githubusercontent.com/creationix/nvm/v0.123.1/install.sh | /bin/bash
 469: [2]: https://github.com/creationix/nvm/blob/v0.123.1/install.sh
package.json
 3:   "version": "0.123.1",
[master de1f255] v0.123.1
 4 files changed, 8 insertions(+), 8 deletions(-)

[PeterDaveHello]

BTW, we'll need to manually change the color to Green or Blue once v1.0 released, any ETA on v1.0 yet?

[ljharb]

Wait, why? I thought it'd always be yellow - pre-1.0 is just as green as post-1.0, since "1.0" means literally nothing about the stability of software.

[PeterDaveHello]

Oh okay, that's from the shieds.io version color rule and we are not using that, if the version doesn't mean any stability, that's no need to do that. (But why roadmap for v1.0?)

[ljharb]

The roadmap for 1.0 is because users have the mistaken belief that 1.0 means something, and so while lots of users will update to a 1.0, fewer will upgrade to v2 or v3 in the future - so i want nvm to have the ability to update itself before 1.0.

[PeterDaveHello]

Okay, so that's for the users, not for real meaning :) Mind to share your expect ETA of v1.0? Maybe move to another issue for that?

[ljharb]

No expected ETA just yet.

[PeterDaveHello]

hmmmm ... next time maybe I should add [skip ci] here

[ljharb]

nah, it's best to let CI always run

[PeterDaveHello]

Even there isn't any part have something to do with README? Maybe we can just save the time and resource on CI.