Update readme with build, see #29 for details

Author: abelbraaksma

README.md

@@ -67,6 +67,45 @@ build help
 
 For more info, see this PR: https://github.com/abelbraaksma/TaskSeq/pull/29.
 
+## Building & testing
+
+TLDR: just run `build`. Or load the `sln` file in Visual Studio or VS Code and compile.
+
+### Prerequisites
+
+* .NET 6 or .NET 7 Preview
+* F# 6.0 compiler
+* To use `build.cmd`, the `dotnet` command must be accessible from your path.
+
+Just checkout this repo. From the root of the repo:
+
+### Build the solution
+
+```
+build [release|debug]
+```
+
+### Run the tests
+
+```
+build test [release|debug]
+```
+
+### Run the CI command
+
+```
+build ci [release|debug]
+```
+
+### Get options
+
+```
+build help
+```
+
+For more info, see this PR: https://github.com/abelbraaksma/TaskSeq/pull/29.
+
+
 ## In progress!!!
 
 It's based on [Don Symes `taskSeq.fs`][10]