Rename all @id in docs

[ytdHuang]

Summary of this PR:

• Delete removed file (install.md)
• add docs/README.md for tutorial of building documentation locally.
• add QuantumToolbox to [deps] in docs/Project.toml (see the tutorial in docs/README.md)
• Rename all @id (as discussed below)

If we define some title as:

# [Some Title](@id doc: Some Title)

We have to reference it with the quotation marks "" due to the blank spaces in @id, namely

... click [here](@ref "doc: Some Title") ...

So I suggest to change the @id naming rule as

# [Some Title](@id doc:Some-Title)

Basically is just remove all blank spaces (and add hyphen - if needed).
In this way, we can just reference it by

... click [here](@ref doc:Some-Title) ...