README: Fix AppVeyor branch and add link to LICENSE

[gerardroche]

• Point AppVeyor status badge to master

[gerardroche]

We could add a table with the status of all minor branches. There's lots of possibilities. This could be on the readme, or a dedicated status on the php.net?

Branch	AppVeyor	Travis CI	Azure Pipelines
master
7.4
7.3			n/a
7.2			n/a
7.1			n/a

Branch	AppVeyor	Travis CI	Azure Pipelines	Bug Fixes Until	Security Fixes Until
master				—	—
7.4
7.3				6 Dec 2020	6 Dec 2021
7.2				30 Nov 2019	30 Nov 2020
7.1				1 Dec 2018	1 Dec 2019

Branch	AppVeyor	Travis CI	Azure Pipelines
master
7.4
7.3
7.2
7.1
7.0
5.6
5.5
5.4
5.3

Branch	AppVeyor	Travis CI	Azure Pipelines	Bug Fixes	Security Fixes
master				—	—
7.4
7.3				6 Dec 2020	6 Dec 2021
7.2				30 Nov 2019	30 Nov 2020
7.1				1 Dec 2018	1 Dec 2019
7.0
5.6
5.5
5.4
5.3

[nikic]

Regarding adding a larger matrix of build badges, I'm neutral on that -- I can't say I ever looked at them ^^ Maybe @petk @carusogabriel @cmb69 have thoughts about this?

[carusogabriel]

I'm neutral, as well. I rarely look into them, I just strait to the respective websites.

Having on the master is interesting, as we need to ensure that this build in specific is always green.

[cmb69]

What would be the benefit of having such a CI badge matrix?

[nikic]

What might be useful would be links to the last scheduled builds on the 7.4/master branch, as those contain our full test matrixes and are not easily accessible right now. Though I'm not sure if there is any way to get the last scheduled build specifically...

[gerardroche]

Having thought about it, there isn't a lot of value of a matrix of build badges. I guess the idea is to try bring more awareness to supported versions, but a matrix of badges on the readme isn't going to achieve that.

I like the supported versions page. I only became aware of it recently. My understanding of supported versions before that was fuzzy. I also think the recent cleanup of the readme and other docs has helped.

What might be useful would be links to the last scheduled builds on the 7.4/master branch, as those contain our full test matrixes and are not easily accessible right now. Though I'm not sure if there is any way to get the last scheduled build specifically...

I looked into it and I can't see a way to do it. CI service APIs generally only allow you to get the status of a branch. Most don't even allow you to get the status of a tag. I'm surprised the Azure UI doesn't have a filter for scheduled builds.