[docs] Add how-to for multi-year investments (#899) #1105

	name: Docs

	on:
	push:
	branches:
	- main
	paths:
	- "docs/**"
	- "src/**"
	- "*.toml"
	tags: ["*"]
	pull_request:
	branches:
	- main
	paths:
	- "docs/**"
	- "src/**"
	- "*.toml"
	types: [opened, synchronize, reopened]

	concurrency:
	# Skip intermediate builds: always.
	# Cancel intermediate builds: only if it is a pull request build.
	group: ${{ github.workflow }}-${{ github.ref }}
	cancel-in-progress: ${{ startsWith(github.ref, 'refs/pull/') }}

	jobs:
	docs:
	name: Documentation
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	- uses: julia-actions/setup-julia@v2
	with:
	version: "1"
	- name: Use Julia cache
	uses: julia-actions/cache@v2
	- name: Instantiate environment with development version of the package
	run: \|
	julia --project=docs -e '
	using Pkg
	Pkg.develop(PackageSpec(path=pwd()))
	Pkg.instantiate()'
	- name: Run doctest
	run: \|
	julia --project=docs -e '
	using Documenter: DocMeta, doctest
	using TulipaEnergyModel
	DocMeta.setdocmeta!(TulipaEnergyModel, :DocTestSetup, :(using TulipaEnergyModel); recursive=true)
	doctest(TulipaEnergyModel)'
	- name: Generate and deploy documentation
	run: julia --project=docs docs/make.jl
	env:
	JULIA_PKG_SERVER: ""
	GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
	DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}
	GKSwstype: "100" # https://discourse.julialang.org/t/generation-of-documentation-fails-qt-qpa-xcb-could-not-connect-to-display/60988

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