mention the need for PythonEngine.Initialize and BeginAllowThreads in…

mention the need for PythonEngine.Initialize and BeginAllowThreads in… · pythonnet/pythonnet@8a52d79

Original file line number	Diff line number	Diff line change
`@@ -50,6 +50,8 @@ Embedding Python in .NET`
`50`	`50`	(internal, derived from ``MissingMethodException``) upon calling ``Initialize``.
`51`	`51`	Typical values are ``python38.dll`` (Windows), ``libpython3.8.dylib`` (Mac),
`52`	`52`	``libpython3.8.so`` (most other Unix-like operating systems).
	`53`	+- Then call ``PythonEngine.Initialize()``. If you plan to use Python objects from
	`54`	+ multiple threads, also call ``PythonEngine.BeginAllowThreads()``.
`53`	`55`	`- All calls to python should be inside a`
`54`	`56`	``using (Py.GIL()) {/* Your code here */}`` block.
`55`	`57`	- Import python modules using ``dynamic mod = Py.Import("mod")``, then