Add httpsoft/http-message info

[vjik]

Q	A
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Related tickets	php-http/discovery#241
Documentation	-
License	MIT

[dbu]

thanks for bringing this up. this prompted me to do #310

there is a misunderstanding here. the factories this documentation talks about are the obsolete PHP-HTTP factories that we did before PSR-17 was a thing. in #310 i update the documentation to explain why the PHP-HTTP factories have been deprecated and abandoned. (and also update various adapter and client docs that had not been updated when we switched to PSR-17)

[dbu]

sorry, i realized that there is more in this pull request that is still relevant.

@nicolas-grekas i realize that the discovery.rst does not list what implementations are supported. i think we should mention that somewhere.

[dbu]

the file to change would not be the ones about the php-http/message-factory but discovery.rst. we currently don't mention the implementations that are discovered but happy if you want to add that in the introduction.

[vjik]

@dbu Do I need to fix something in the current PR?

[dbu]

its probably best to start with a fresh PR if you want discovery to mention all implementations it might install.

the changes in this PR are all about the deprecated php-http/message-factory (which httpsoft does not implement), so i think they are a misunderstanding.

[vjik]

OK, may be later...

[dbu]

glad if you want to add something, or somebody else might at some point adds the list of discovered clients. i will close this PR.