@posts/PrincipalComponentAnalysis.md; improves

Is followup to: commit a2ffd7c (@`posts/PrincipalComponentAnalysis.md`; `remark-lint`). TODO: `squash` group this
@`./posts/PrincipalComponentAnalysis.md`:
	+`./posts/images/Comparison_of_graphical_projections.svg`
	Extra whitespaces in code blocks (`` ``` ... ``` ``) removed.
	`:%s/^    /> /`: replaces block code with block quotes.
	+`#discussion`, +`#discussion-12`, +`#discussion-2`, +`#discussion-22`:
		Previous post, except synopsis
	+`#discussion-22`: new discussion with *Solar-Pro-2* which includes `java` source code uses *Principle Component Analysis*.
	+`#synopsis--similar-posts`

Author: SwuduSusuwu