Update nvm

update_nvm.md

Update nvm

Official manual upgrade instructions
https://github.com/nvm-sh/nvm#manual-upgrade

(
  cd "$NVM_DIR"
  git fetch --tags origin
  git checkout `git describe --abbrev=0 --tags --match "v[0-9]*" $(git rev-list --tags --max-count=1)`
) && \. "$NVM_DIR/nvm.sh"

Slightly simplified:

(
  cd "$NVM_DIR"
  git fetch --tags origin
  git checkout "$(git describe "$(git rev-list --tags="v[0-9]*" --max-count=1)")"
) && \. "$NVM_DIR/nvm.sh"

Simplifications:

1. Move the pattern check to the rev-list command: --tags="v[0-9]*"
2. Remove --tags from the describe command because we already restricted the lookup to being a tag
3. Remove --abbrev=0 from the describe command because it serves no purpose.