Update GitLab Dedicated handbook page

Why is this change being made?

💡 Provide a detailed answer to the question on why this change is being proposed, in accordance with our value of Transparency.

As I am going through my onboarding issue, I have found a handful of broken links, outdated references, and typos to update in the GitLab Dedicated handbook page. I propose updating these (especially the outdated references) to ensure those onboarding after me and any other newcomers to Dedicated have an accurate picture of our current status.

The proposed changes are summarized below:

• Updating references to the GitLab Dedicated - Limited Availability epic under Epic Hierarchy as this is now complete.
• Removing reference to the Cross Functional Initiatives as these are now deprecated (see What were Top Cross-Functional Initiatives?)
• Add dedicated_team_logo.png under content/.../team/gitlab-dedicated/img/ dir so it will populate properly on the GitLab Dedicated page.
• Fix minor typos

%{all_commits}

Author and Reviewer Checklist

Please verify the check list and ensure to tick them off before the MR is merged.

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added, and the content is SAFE
• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
  • The when to get approval handbook section explains the workflow in more detail
• For transparency, share this MR with the audience that will be impacted.
  • Team: For changes that affect your direct team, share in your group Slack channel
  • Department: If the update affects your department, share the MR in your department Slack channel
  • Company: If the update affects all (or the majority of) GitLab team members, post an update in #whats-happening-at-gitlab linking to this MR
    • For high-priority company-wide announcements work with the internal communications team to post the update in #company-fyi and align on a plan to circulate in additional channels like the "While You Were Iterating" Newsletter

---