Documentation: Centralize docs into docs.excel-dna.net

[augustoproiete]

• [ ] Add documentation from the ExcelDna wiki
• [ ] Add documentation from the Registration wiki
• [ ] Add documentation from the IntelliSense wiki
• [ ] Add documentation from the ExcelDnaDoc website (repository)
• [x] Add documentation from the CodePlex archive (#309) (https://github.com/Excel-DNA/docs.excel-dna.net/pull/5)
• [x] Add reference to the Samples repo
• [x] Add reference to the WiXInstaller repo
• [ ] Add reference to the ExcelDna.StrongName repo

[rkapl123]

I think "Add reference to the Samples repo" has been done in docs.excel-dna.net. I've also added the reference to the WixInstaller repo and the ExcelDna.StrongName to the 3rd party tools.