documentation: Re-org for "closer-look" chapter

Fixes [YOCTO #11630]

The ref-manual needs expansion for the old "closer-look" chapter.
This chapter previously held a detailed look at what happens when
a user uses the YP to develop something.  Now, the chapter needs
to also contain YP development environment concepts (e.g. open-
source philosophy, etc.), which are coming from the dev-manual.

Because of this, I renamed the "closer-look.xml" chapter to be
"ref-development-environment.xml".  I also renamed the larger
section that was formerly the entire chapter into its own section
named "Development Concepts".

Both these changes caused a few links to break.  I fixed all the
links from within the various manuals so they would find appropriate
targets.

I did some re-writing for introductory material to introduce the new
chapter and the section on "Development Concepts".

A new file ("ref-development-environment.xml") was added by basically
renaming the "closer-look.xml" chapter.  And, the tracking for
"closer-look.xml" was deleted.

(From yocto-docs rev: e37806474578b4f0ed137f64d68a39a17ab60644)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/yocto-project-qs/yocto-project-qs.xml

@@ -948,7 +948,7 @@
                     You can get
                     <ulink url='&YOCTO_DOCS_REF_URL;#usingpoky'>build details</ulink>,
                     a
-                    <ulink url='&YOCTO_DOCS_REF_URL;#closer-look'>closer look</ulink>
+                    <ulink url='&YOCTO_DOCS_REF_URL;#development-concepts'>closer look</ulink>
                     at how the pieces of the Yocto Project development
                     environment work together, information on various
                     <ulink url='&YOCTO_DOCS_REF_URL;#technical-details'>technical details</ulink>,