[Docs] Add reminder that NVM_DIR should not contain trailing slash, fix for #1708
[Docs] Add reminder that NVM_DIR should not contain trailing slash, fix for #1708

PeterDaveHello/nvm,ljharb/nvm,PeterDaveHelloKitchen/nvm,PeterDaveHello/nvm,PeterDaveHelloKitchen/nvm,creationix/nvm,edwmurph/nvm,evocateur/nvm,evocateur/nvm,creationix/nvm,ljharb/nvm,edwmurph/nvm