Documentation fixes and additions

[jeandemanged]

Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines

Does this PR already have an issue describing the problem?

No

What kind of change does this PR introduce?

Bugfix/documentation

What is the current behavior?

• api change from #704 (add_disconnection)
• incorrect svg file name from #689
• missing operator strategy methods in api reference / from #621
• other minor warnings

What is the new behavior (if this is a feature change)? no doc build warnings/errors

Does this PR introduce a breaking change or deprecate an API?

• [x] No