Add doap.xml

[stokito]

The doap.xml contains a list of supported XEPs. The XMPP.org collects the doap.xml and shows them on https://xmpp.org/software/
E.g. open https://xmpp.org/software/qxmpp/ and click on "Show supported XEPs".
This doap file in sources https://invent.kde.org/libraries/qxmpp/-/blob/master/doc/doap.xml?ref_type=heads

This doap file in sources https://invent.kde.org/libraries/qxmpp/-/blob/master/doc/doap.xml?ref_type=heads

See XEP-0453: DOAP usage in XMPP.

After merging of the PR we'll need to change the https://github.com/xsf/xmpp.org/blob/master/data/software.json to add a link to the doap.

The DOAP in the PR contains only one XEP that I found. Please add any others yourself.

[vitalyster]

XMPP had its bad reputation for their XEPs poorly implemented in different clients and their poor interoperability. Now you want me to take care of another poorly implemented XEP. Please, take care of it and complete your work, otherwise we don't need to advertise wrong information on xmpp.org, sorry

[vitalyster]

Information is inaccurate

[stokito]

Things gets better, eventually interoperability will be on a good level. Basically here I wish to to improve it a little bit by the XEP-0453: DOAP usage in XMPP.
This PR can be a good start. The provided information is not required to be accurate, this is more information for users who need to briefly estimate the lib features. The XMPP.org introduced the doap.xml files because with it a developers can provide the information themselves. As a developer you can specify all the supported or planed XEPs.

[stokito]

Hi @vitalyster could you merge the PR so that the library will be seen on the XMPP.org? If anything needs to be changed you can do this yourself when you'll have a time.
Thank you

[vitalyster]

@stokito this is your PR and you must address its issues. Nobody will fix your work for you.

[stokito]

Which issues?

[vitalyster]

@stokito Please, read my first reply again.