missing tensorflow-lite package-config file after installation

[LucasLvbj]

where: doc of "Post-Processing with TensorFlow Lite" -> "Prerequisites"
Issue description:

• after download and install a version that exports the API from [lindevs.com], and try to recompile rpicam-apps with TensorFlow Lite support].
• at step: "meson setup build -Denable_libav=enabled -Denable_drm=enabled -Denable_egl=enabled -Denable_qt=enabled -Denable_opencv=enabled -Denable_tflite=enabled", got error [ERROR: dependency "tensorflow-lite" not found]
• after google, this seems solved in The tflite package may not have .pc files, so meson may not find the libraries rpicam-apps#622, but not reflected in doc. Suggest to update doc.

[lurch]

ping @davidplowman and @naushir