Documentation: use JSON instead of the deprecated JSON3 once CTModels is released #993

Context

JSON3.jl is deprecated in favour of JSON.jl v1. CTModels moves its JSON format to JSON.jl (control-toolbox/CTModels.jl#467, PR #468): the CTModelsJSON extension is then activated by using JSON instead of using JSON3, and JSON3Tag is renamed JSONTag. format=:JSON is unchanged and the files keep their format.

This is a breaking change of CTModels (0.20.0). Once it is released, the OptimalControl documentation must load JSON instead of JSON3, or the JSON examples will fail with an ExtensionError.

To update (after the CTModels release)

• docs/make.jl: using JSON3 → using JSON.
• docs/src/results/save-load.md:
  • the JSON section: the link to JSON3.jl → JSON.jl, and using JSON3 → using JSON;
  • the section "Without JLD2 or JSON3" (title and text): JSON; the ExtensionError for format=:JSON now names JSON.
• docs/src/getting-started/installation.md: using JSON3 # format=:JSON → using JSON.
• The documentation environments, which list JSON3 with its UUID and a [compat] entry: JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6" and JSON = "1" in
  • docs/Project.toml;
  • docs/src/assets/Project.toml;
  • docs/src/public/assets/Project.toml.
• Check the notebook and script of the guided tour (docs/src/public/assets/guided-tour.*) and the pages that mention the formats.

Nothing in src/, ext/ or test/ of OptimalControl uses JSON3.

Related

• Replace the deprecated JSON3.jl by JSON.jl v1 (rename JSON3Tag to JSONTag) CTModels.jl#467, CompatHelper: bump compat for CTBase to 0.16, (drop existing compat) #468.
• OptimalControl#992 (documentation of the multi-phase solutions), which depends on the same CTModels release.