Update outdated _config.yml variables to reflect April 2026 state

[devdavidejesus]

Related: #4662

Summary

The _config.yml file contains a comment indicating "Values last updated 2018-10-16" for several variables used across multiple pages of the site (full-node descriptions, block chain size references, mining reward mentions). This PR updates the outdated values to reflect the current state of the Bitcoin network as of April 2026.

Changes

Variable	Before	After	Source
subsidy_in_decimal_bitcoins	6.25	3.125	Fourth halving, April 20, 2024 (block 840,000)
bitcoin_datadir_gb	350	750	Actual size: 733.24 GB on April 13, 2026 (YCharts). Value set slightly higher per the file's own guidance: "For increasing variables, like chain size, choose a somewhat higher value so we don't need to update too often."
chain_gb	340	740	Adjusted proportionally to bitcoin_datadir_gb, maintaining the original ~10 GB gap for chainstate and block indices.
total_tx_count_in_millions	230	1300	Bitcoin network surpassed 1 billion transactions on May 5, 2024. YCharts reports 1.292B as of January 1, 2026. Value set with margin for growth.
Comment	"Values last updated 2018-10-16"	"Values last updated 2026-04-17"	—

Notes

• The bitcoin_datadir_gb_pruned: 7 variable was intentionally left unchanged, as 7 GB remains the documented minimum for running a pruned node (per bitcoin.org/en/full-node).
• The updated values affect descriptions across multiple pages of the site via the site.text.* variables, including the full-node page, wallet validation descriptions, and initial sync notes.

[devdavidejesus]

Just checking if there’s any feedback on this. @Cobra-Bitcoin
Tks

[Cobra-Bitcoin]

LGTM. Thank you!

[devdavidejesus]

Tks @Cobra-Bitcoin