Update Qt Creator Manual according to the change log.

New features:

• Markdown editor: https://doc-snapshots.qt.io/qtcreator-11.0/creator-markdown-editor.html
• Built-in terminal: https://doc-snapshots.qt.io/qtcreator-11.0/creator-output-panes.html#terminal
• vcpkg support (Expanding Qt projects with 3rd party libraries): https://doc-snapshots.qt.io/qtcreator-11.0/creator-vcpkg.html 
• Copilot: https://doc-snapshots.qt.io/qtcreator-11.0/creator-copilot.html
• Axivion: https://doc-snapshots.qt.io/qtcreator-11.0/creator-axivion.html 

Other planned changes:

• [A long-term goal that will not happen in 11.0] Move detailed information about preferences and other buttons and fields from the manual into tooltips in the UI
• [Done] Improve descriptions of project wizard templates in the UI and remove them from the manual
• [Done] Improve tooltips/help for the locator in the UI and remove the filter information from the manual
• [Done] Update icons on the front page to use versions of the mode bar icons
• Improve plugin descriptions in the UI and add links to the plugin docs (Check that all plugins have places to link to. What to do with undocumented plugins?)
• [Done] Try to make the All Topics more visible for users who want a flat view of all sections in the manual for searching
• [Done] Improve the change log to contain sections that describe the new features instead of just a list of what changed