docs: remove old sections

Author: thephez

docs/user/developers/testnet.rst

@@ -53,6 +53,7 @@ specific service.
 - **Discussion and help:** https://www.dash.org/forum/index.php?forums/testing.53/
 - **Android wallet:** https://github.com/dashpay/dash-wallet/releases/latest
 - **Testnet for Bitcoin:** https://en.bitcoin.it/wiki/Testnet
+- **Release notes for previous versions:** https://github.com/dashpay/dash/tree/master/doc/release-notes/dash
 
 Faucets
 -------
@@ -89,126 +90,3 @@ but with a few key differences:
 - As for mainnet masternodes, the RPC username and password must contain
   alphanumeric characters only
 
-Testnet 0.16.0
-==============
-
-In June 2020, the Dash team announced the start of testing of the
-upcoming Dash 0.16.0 release. Extensive internal testing has already been
-done on the 0.16.0 code, but there are numerous bugs that can only be
-revealed with actual use by real people. The Dash team invites anybody
-who is interested to download the software and become active on testnet.
-This release includes:
-
-- Block reward reallocation
-- Core Wallet UI/UX Improvements
-- Quorum Signing Optimizations
-- Network Threading Improvement
-- Minimum Protocol Check
-- Bitcoin 0.16 and 0.17 Backports
-
-Discussion:
-
-- Testnet announcement: https://www.dash.org/forum/threads/v0-16-testing.50294/
-- Product brief: https://blog.dash.org/updated-product-brief-dash-core-release-v0-16-0-d3debdb6242e
-
-Testnet 0.15.0
-==============
-
-In December 2019, the Dash team announced the start of testing of the
-upcoming Dash 0.15.0 release. Extensive internal testing has already been
-done on the 0.15.0 code, but there are numerous bugs that can only be
-revealed with actual use by real people. The Dash team invites anybody
-who is interested to download the software and become active on testnet.
-This release includes:
-
-- Bitcoin 0.15 backports
-- Removal of legacy code
-
-Discussion:
-
-- Testnet announcement: https://www.dash.org/forum/threads/v15-0-testing.49140/
-- Product brief: https://blog.dash.org/product-brief-dash-core-release-v0-15-0-acd7633a91ab
-
-Testnet 0.14.0
-==============
-
-In March 2019, the Dash team announced the start of testing of the
-upcoming Dash 0.14.0 release. Extensive internal testing has already been
-done on the 0.14.0 code, but there are numerous bugs that can only be
-revealed with actual use by real people. The Dash team invites anybody
-who is interested to download the software and become active on testnet.
-This release includes:
-
-- LLMQ DKGs
-- LLMQ based ChainLocks
-- LLMQ based InstantSend
-
-Discussion:
-
-- Testnet announcement: https://www.dash.org/forum/threads/v14-0-testing.44047/
-- Product brief: https://blog.dash.org/product-brief-dash-core-release-v0-14-0-now-on-testnet-8f5f4ad45c96
-
-Testnet 0.13.0
-==============
-
-In November 2018, the Dash team announced the start of testing of the
-upcoming Dash 0.13.0 release. Extensive internal testing has already been
-done on the 0.13.0 code, but there are numerous bugs that can only be
-revealed with actual use by real people. The Dash team invites anybody
-who is interested to download the software and become active on testnet.
-This release includes:
-
-- Automatic InstantSend for Simple Transactions
-- Deterministic Masternode List
-- 3 Masternode Keys: Owner, Operator and Voting
-- Special Transactions
-- PrivateSend Improvements
-
-Discussion: 
-
-- Testnet announcement: https://www.dash.org/forum/threads/v13-0-testing.41945/
-- Product brief: https://blog.dash.org/product-brief-dash-core-release-v0-13-0-5d7fddffb7ef
-
-Testnet 0.12.3
-==============
-
-In June 2018, the Dash team announced the start of testing of the
-upcoming Dash 0.12.3 release. Extensive internal testing has already been
-done on the 0.12.2 code, but there are numerous bugs that can only be
-revealed with actual use by real people. The Dash team invites anybody
-who is interested to download the software and become active on testnet.
-This release includes:
-
-- Named Devnets, to help developers quickly create multiple independent
-  devnets
-- New format of network message signatures
-- Governance system improvements
-- PrivateSend improvements
-- Additional indexes cover P2PK now
-- Support for pruned nodes in Lite Mode
-- New Masternode Information Dialog
-
-Discussion:
-
-- https://www.dash.org/forum/threads/v12-3-testing.38475/
-
-Testnet 0.12.2
-==============
-
-In October 2017, the Dash team announced the launch of a testnet for
-public testing of the upcoming 0.12.2 release of the Dash software.
-Extensive internal testing has already been done on the 0.12.2 code, but
-there are numerous bugs that can only be revealed with actual use by
-real people. The Dash team invites anybody who is interested to download
-the software and become active on testnet. This release includes:
-
-- DIP0001 implementation https://github.com/dashpay/dips/blob/master/dip-0001.md
-- 10x transaction fee reduction (including InstantSend fee)
-- InstantSend vulnerability fix
-- Lots of other bug fixes and performance improvements
-- Experimental BIP39/BIP44 compliant HD wallet (disabled by default, should be fully functional but there is no GUI yet)
-
-Discussion:
-
-- Testnet 12.2 discussion: https://www.dash.org/forum/threads/v12-2-testing.17412/
-- Testnet tools: https://www.dash.org/forum/threads/testnet-tools-resources.1768/