docs(faq): moved the filtering page from docs

ref: #6812
docs(faq): moved the css is missing page from docs

ref: #6812
docs(faq): move the Should I edit the database manually page from docs

ref: #6812
docs(faq): moved the page not found page from docs

ref: #6812
docs(faq): moved the IE login problem page from docs

ref: #6812
docs(faq): moved the What variables are reserved by Elgg page from docs

ref: #6812
docs(plugins): moved the System diagnostics page from docs

ref: #6812
docs(faq): moved Emails don't support non-Latin characters from docs

ref: #6812
docs(faq): moved the session length page from docs

ref: #6812
docs(faq): moved the Copy a plugin page from docs

ref: #6812
docs(faq): moved the File is missing an owner page from docs

ref: #6812
docs(faq): moved the No images page from docs

ref: #6812
docs(guides): moved the systemlog page from docs

ref: #6812
docs(faq): moved the Deprecation warnings page from docs

ref: #6812
docs(faq): moved the Javascript not working page from docs

ref: #6812
docs(design): moved the Loggable page from docs

ref: #6812
docs(guides): moved the Accessibility Guidelines from docs

ref: #6812
docs(guides): moved Walled Garden page from docs

ref: #6812