What tool could be used to create a product documentation?

I love Confluence. It's great for creating a collaborative knowledge space. I've also used MS Teams to organize by Product (Team) and then post the documents under Files (which is SharePoint in the backend).

the company where I work doesn't have any product documentation yet, this is starting to jeopardize the development team.

I work in an IT Company. 

I wonder if you could suggest any tool that could be used for product documentation. I heard Confluence could be a nice tool for this purpose, but I would like to listen to the opinion of this awesome community.

Why not start with the team's Definition of Done and work forward from there.

If an increment is to be of release quality:

• what sort of documentation is actually required (e.g. technical reference, release notes, user guides)
• what standards will be applied to its production (e.g. branding, internationalization, accessibility),
• how will quality be assured by the Development Team,
• what skills will be needed to develop it (e.g. technical writing, language skills),
• who is intended to consume it,
• how ought it to be version controlled,
• how will feedback be elicited, and
• how ought it to be communicated/disseminated to stakeholders and subsequently updated

I would like to suggest you use zentao project management tool. It also has a trial version without any initial payment plan selection so you can decide if it works for you.When collaborating with a team, there is no better tool than zentao.

For me, the contention lays between product documentation and product backlog. If product documentation is impeding the development I presume you are actually referring to not having a proper product backlog. 

Ownership of the product backlog sits squarely with the PO and there are many tools out there for product backlog management (VersionOne, Jira, Rally software, TFS. etc.)

With respect to having product documentation for the purpose of training and help files, there are ways and means to extract product documentation from the product backlog at a point in time to Excel, Confluence, etc. This would ensure that the product documentation is always up to date and just good enough.