[amber-docs] RFR: Revise and restructure for the new web-page generator

[Mark Reinhold]

Please review these changes to revise and restructure the amber-docs repository for use with the new web-page generator for `openjdk.java.net`.

That generator is presently defined in https://github.com/mbreinhold/ojweb-generate, which will shortly be moved over to the OpenJDK organization. Please see the `README.md` file in that repository for instructions on how to use it.

I’ve tried to keep content changes to a minimum, primarily adjusting minor things such as heading levels and code examples for better rendering.

You can preview the output here: https://openjdk.java.net/_test/amber/

For easy reviewing, there’s also a map of the entire subtree: https://openjdk.java.net/_test/amber/_map

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Commit messages:
 - Drop execute bits on text files
 - Use a real Makefile instead of a symbolic link
 - Further minor layout tweaks
 - Restructure templated-strings.md, and add it to the project page
 - Merge remote-tracking branch 'origin/master' into ojweb
 - Create symbolic link to ojweb-generate/Makefile
 - Update .gitignore
 - Remove old publication infrastructure
 - Extending switch for Patterns: Expose inherent list structure
 - Text blocks guide: Shift position of table of contents
 - ... and 17 more: https://git.openjdk.java.net/amber-docs/compare/c182d1e6...b198f1b6

Changes: https://git.openjdk.java.net/amber-docs/pull/10/files
 Webrev: https://webrevs.openjdk.java.net/?repo=amber-docs&pr=10&range=00
  Stats: 3116 lines in 27 files changed: 223 ins; 1841 del; 1052 mod
  Patch: https://git.openjdk.java.net/amber-docs/pull/10.diff
  Fetch: git fetch https://git.openjdk.java.net/amber-docs pull/10/head:pull/10

PR: https://git.openjdk.java.net/amber-docs/pull/10