some comments on the logger implemenetaiton

[fnrizzi]

https://github.com/Pressio/pressio-log/blob/main/include/pressio-log/logger/logger.hpp

• we are missing move assign and move constructor

pressio-log/include/pressio-log/logger/logger.hpp

Lines 73 to 75 in 6752bc0

	// Delete copy and assignment ops
	Logger(Logger &other) = delete;
	void operator=(const Logger &) = delete;

• we need to write a better explanation of the pattern used here

pressio-log/include/pressio-log/logger/logger.hpp

Lines 77 to 81 in 6752bc0

	// Return singleton instance of PressioLogger
	static std::shared_ptr<Logger> PressioLogger() {
	static std::shared_ptr<Logger> instance(new Logger());
	return instance;
	}

so that if we read this later or if someone else picks this up, they know what is going on here.
This is a good page to either reference or take some things from: https://blog.mbedded.ninja/programming/languages/c-plus-plus/magic-statics/

[cwschilly]

This work has been added to main