add port plugins documentation

Docs/port-plugins.md

@@ -0,0 +1,17 @@
+# Porting Wox Plugins
+
+Note:
+- When porting, please keep the author's commit history
+- Flow Launcher targets .Net Core 3.1, so plugins should also be upgraded to keep the continuity of future developments
+
+Steps:
+1. to start off, you can fork/create a new repo, either way the project's commit history must be kept. If it's forked, you can just start updating it. If it's a new repo, do this by first cloning the repo, then add your new repo as a new repo remote, remove the original remote and then push to it.
+2. use try convert tool from https://github.com/dotnet/try-convert
+3. try-convert -w path-to-folder-or-solution-or-project
+4. May need to fix on the project file, a good template to follow is the [Explorer plugin](https://github.com/Flow-Launcher/Flow.Launcher/blob/dev/Plugins/Flow.Launcher.Plugin.Explorer/Flow.Launcher.Plugin.Explorer.csproj) project:
+	- fix <TargetFramework> to netcoreapp3.1
+	- set the output location as 'Output\Release\<name of the project>'
+	- add <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies> and <AppendTargetFrameworkToOutputPath>false</AppendTargetFrameworkToOutputPath>
+	- bump version to 2.0.0 and fix up any missing attributes if neccessary
+5. update code and fix plugin's setting layout if neccessary
+6. update readme to indicate where this port is from and the original author of the project