Manual installation without using an install command

I would like to be able to install `nvs` in an arbitrary location, which would be a user-owned subdirectory of `/usr/local`, and *manually* update `$HOME/.profile` _(I do not care about updating any files other than `$HOME/.profile`)_. _(When I tried `. "$NVS_HOME/nvs.sh" install` with `nvs` in a subdirectory of `/user/local`, using my own user id, it tried to update a root `profile` file which neither works nor is what I want to do.)_

The motivation is that it would make it easier for me to start `pm2` as root (in its "god" mode) then control it from my own user account.

_P.S. This is for a Ubuntu 18.04 LTS server droplet on Digital Ocean. I was already able to do this one one droplet. I will now try this on another droplet and give the solution in a comment for the sake of others. I think this manual installation should be documented as an option, hope I get a chance to raise a PR someday. I accidentally submitted before I finished adding the information, apologies._

Start with the installation flow represented by `. "$NVS_HOME/nvs.sh" install`, including how `$HOME/.profile` is handled for an arbitrary user-owned location. Document a manual installation option that avoids updating a root profile and clearly explains the expected setup for controlling nvs and pm2.

Written by the indexing model from the issue text.