docs: better docs, mv doxygen to sphinx

This patch refactors the VPP sphinx docs
in order to make it easier to consume
for external readers as well as VPP developers.

It also makes sphinx the single source
of documentation, which simplifies maintenance
and operation.

Most important updates are:

- reformat the existing documentation as rst
- split RELEASE.md and move it into separate rst files
- remove section 'events'
- remove section 'archive'
- remove section 'related projects'
- remove section 'feature by release'
- remove section 'Various links'
- make (Configuration reference, CLI docs,
  developer docs) top level items in the list
- move 'Use Cases' as part of 'About VPP'
- move 'Troubleshooting' as part of 'Getting Started'
- move test framework docs into 'Developer Documentation'
- add a 'Contributing' section for gerrit,
  docs and other contributer related infos
- deprecate doxygen and test-docs targets
- redirect the "make doxygen" target to "make docs"

Type: refactor

Change-Id: I552a5645d5b7964d547f99b1336e2ac24e7c209f
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>

test/Makefile

@@ -14,7 +14,6 @@ ifndef TEST_DIR
 endif
 
 export TEST_BR = $(TEST_DIR)
-export TEST_DOC_BR = $(TEST_DIR)/doc/build
 FAILED_DIR=/tmp/vpp-failed-unittests/
 VPP_TEST_DIRS=$(shell ls -d $(TEST_DIR) $(EXTERN_TESTS))
 
@@ -239,21 +238,6 @@ wipe: reset
 	@rm -rf $(VENV_PATH)
 	@rm -rf $(patsubst %,%/__pycache__, $(VPP_TEST_DIRS))
 
-$(TEST_DOC_BR): $(PIP_INSTALL_DONE)
-	@mkdir -p $@
-	@bash -c "source $(VENV_PATH)/bin/activate && make -C doc html"
-
-.PHONY: doc
-doc: $(PIP_PATCH_DONE) $(TEST_DOC_BR)
-	@echo
-	@echo "Test Documentation URL: $(TEST_DOC_BR)/html/index.html"
-	@echo "Run 'make test-wipe-doc test-doc' to rebuild the test docs"
-	@echo
-
-.PHONY: wipe-doc
-wipe-doc:
-	@rm -rf $(TEST_DOC_BR)
-
 $(BUILD_COV_DIR):
 	@mkdir -p $@
 
@@ -279,7 +263,7 @@ wipe-papi:
 	@rm -rf $(PAPI_INSTALL_DONE) $(PAPI_WIPE_DIST)
 
 .PHONY: wipe-all
-wipe-all: wipe wipe-papi wipe-doc wipe-cov
+wipe-all: wipe wipe-papi wipe-cov
 	@rm -rf $(TEST_BR)
 
 .PHONY: checkstyle-diff
@@ -333,9 +317,8 @@ help:
 	@echo " test-gcov                      - build and run functional tests (gcov build)"
 	@echo " test-wipe              - wipe (temporary) files generated by unit tests"
 	@echo " test-wipe-cov          - wipe code coverage report for test framework"
-	@echo " test-wipe-doc          - wipe documentation for test framework"
 	@echo " test-wipe-papi         - rebuild vpp_papi sources"
-	@echo " test-wipe-all          - wipe (temporary) files generated by unit tests, docs, and coverage"
+	@echo " test-wipe-all          - wipe (temporary) files generated by unit tests, and coverage"
 	@echo " test-shell             - enter shell with test environment"
 	@echo " test-shell-debug       - enter shell with test environment (debug build)"
 	@echo " test-checkstyle        - check PEP8 compliance for test framework"
@@ -405,10 +388,6 @@ help:
 	@echo " VPP_IN_GDB_NO_RMDIR=0  - don't remove existing tmp dir but fail instead"
 	@echo " VPP_IN_GDB_CMDLINE=1   - add 'interactive' to VPP arguments to run with command line"
 	@echo ""
-	@echo "Creating test documentation"
-	@echo " test-doc               - generate documentation for test framework"
-	@echo " test-wipe-doc          - wipe documentation for test framework"
-	@echo ""
 	@echo "Creating test code coverage report"
 	@echo " test-cov               - generate code coverage report for test framework"
 	@echo " test-wipe-cov          - wipe code coverage report for test framework"