Rename "npm" make task to "install"

Author: bbatsov

Makefile

@@ -1,9 +1,9 @@
-.PHONY: npm build deploy
+.PHONY: install build
 .DEFAULT_GOAL := build
 
-npm: package.json
+install: package.json
 	npm install --no-fund --no-audit --no-progress --save-dev --loglevel=error
 	npm run antora -- --version
 
-build: npm
+build: install
 	npm run antora -- --fetch antora-playbook.yml

README.adoc

@@ -26,7 +26,7 @@ Installing Antora is super simple:
 
 [source]
 ----
-$ make npm
+$ make install
 ----
 
 Check out https://docs.antora.org/antora/3.1/install/install-antora/[the detailed installation instructions]