docs: refresh & structure overhaul

Rework the doc in order to improve the navigation experience and to make
it easier to update the doc:

- simplify structure: docs/{release-notes,user,developer}
- recreate sphinx config file
- switch theme from opnfv to piccolo
- fix minor rst issues
- fix external references
- add missing license headers (add a short header with copyright and
  SPDX license identifier to the files lacking the information.  The
  header is based on https://github.com/david-a-wheeler/spdx-tutorial)

Change-Id: I9a1135a2873d9955beb26760e0cb6c5d6c1326bd
Signed-off-by: Gwenael Lambrouin <gwenael.lambrouin@orange.com>

1 files changed, 0 insertions, 4 deletions

diff --git a/docs/testing/user/userguide/_static/custom.css b/docs/testing/user/userguide/_static/custom.css
deleted file mode 100644
index 6cbfde3..0000000
--- a/docs/testing/user/userguide/_static/custom.css
+++ /dev/null
@@ -1,4 +0,0 @@
-.wy-nav-content {
-    max-width: 1200px !important;
-}
-