feat: new FindPython support (#2370)

* feat: FindPython support

* refactor: rename to PYBIND11_FINDPYTHON

* docs: Caps fixes

* feat: NOPYTHON mode

* test: check simple call

* docs: add changelog/upgrade guide

* feat: Support Python3 and Python2

* refactor: Use targets in tests

* fix: support CMake 3.4+

* feat: classic search also finds virtual environments

* docs: some updates from @wjakob's review

* fix: wrong name for QUIET mode variable, reported by @skoslowski

* refactor: cleaner output messaging

* fix: support debug Python's in FindPython mode too

* fixup! refactor: cleaner output messaging

* fix: missing pybind11_FOUND and pybind11_INCLUDE_DIR restored to subdir mode

* fix: nicer reporting of Python / PyPy

* fix: out-of-order variable fix

* docs: minor last-minute cleanup
diff --git a/docs/advanced/embedding.rst b/docs/advanced/embedding.rst
index 3930316..98a5c52 100644
--- a/docs/advanced/embedding.rst
+++ b/docs/advanced/embedding.rst
@@ -18,7 +18,7 @@
 
 .. code-block:: cmake
 
-    cmake_minimum_required(VERSION 3.0)
+    cmake_minimum_required(VERSION 3.4)
     project(example)
 
     find_package(pybind11 REQUIRED)  # or `add_subdirectory(pybind11)`