implements different disk sizes for different networks on intro

- Creates m_assumed_blockchain_size and m_assumed_chain_state_size on CChainParams.
- Implements access to CChainParams' m_assumed_blockchain_size and m_assumed_chain_state_size on node interface.
- Implements m_assumed_blockchain_size and m_assumed_chain_state_size on qt/intro via node interface.
- Updates release process document with the new CChainParam's values.

src/chainparams.h

@@ -67,6 +67,10 @@ public:
     /** Policy: Filter transactions that do not match well-defined patterns */
     bool RequireStandard() const { return fRequireStandard; }
     uint64_t PruneAfterHeight() const { return nPruneAfterHeight; }
+    /** Minimum free space (in GB) needed for data directory */
+    uint64_t AssumedBlockchainSize() const { return m_assumed_blockchain_size; }
+    /** Minimum free space (in GB) needed for data directory when pruned; Does not include prune target*/
+    uint64_t AssumedChainStateSize() const { return m_assumed_chain_state_size; }
     /** Make miner stop after a block is found. In RPC, don't return until nGenProcLimit blocks are generated */
     bool MineBlocksOnDemand() const { return fMineBlocksOnDemand; }
     /** Return the BIP70 network string (main, test or regtest) */
@@ -87,6 +91,8 @@ protected:
     CMessageHeader::MessageStartChars pchMessageStart;
     int nDefaultPort;
     uint64_t nPruneAfterHeight;
+    uint64_t m_assumed_blockchain_size;
+    uint64_t m_assumed_chain_state_size;
     std::vector<std::string> vSeeds;
     std::vector<unsigned char> base58Prefixes[MAX_BASE58_TYPES];
     std::string bech32_hrp;