Added markdown files for openApi3 specifications

[Ngriffiths1]

Added Markdown files for all public facing specification that have been converted to OpenAPI3;

• charges.html.md;
• companyAddress.html.md;
• companyOfficerList.html.md;
• companyProfile.html.md;
• companyRegisters.html.md;
• companyUKEstablishments.html.md;
• disqualifications.html.md;
• /exemptions.html.md;
• filingHistory.html.md;
• index.html.md (this is the search.json schema but the tooling required one file as a homepage and chose this to be the homepage of index.html.md);
• insolvency.html.md;
• officerAppointmentList.html.md;
• psc.html.md;