docs(web): ground the name in the suiko rice-seed loan, Plantare as its inverse

docs/what-is-tane.md

@@ -56,16 +56,19 @@ put away. For all ages, from 10 to 80.
 ## A Japanese name
 
 **Tane** means "seed" (種); *tanemaki* (種まき) means "to sow seeds". And it's no accident
-that the name is Japanese. In much of rural Japan, farming life rested on mutual aid —
-*yui* (結): neighbours lent one another their labour, and their seed and rice too. Whoever
-received grain or seed in a hard year gave it back after the harvest — a little of the
-much that seed had multiplied. That way the common stock never ran dry: every loan, once
-grown, gave back more than it took.
+that the name is Japanese. In early Japan (8th–10th centuries) there was the *suiko* (出挙):
+rice from the granaries was lent out as seed in spring and returned in autumn, after the
+harvest. It began as relief — giving grain to those who had none to sow — but it was repaid
+with interest (from half as much again up to double the loan), and over time it hardened
+into an obligation that left peasants in debt harvest after harvest. The same sack of rice
+was at once seed, food and debt.
 
-That very idea is the heart of Tane. When you share seeds you can attach a **Plantare**: a
-promise to return, when you can, a similar amount of free seed. It isn't a debt — it's a
-pledge to keep the seed alive and moving. And because returning it means growing it, and
-growing multiplies it, every loan makes the commons grow instead of shrinking it.
+Tane keeps that age-old gesture — lending seed and giving it back after the harvest — but
+takes out the trap. When you share seeds you can attach a **Plantare**: a promise to
+return, when you can, a similar amount of free seed. It is not a debt and carries no
+interest: it is a pledge to keep the seed alive and moving. And because returning it means
+growing it, and growing multiplies it, every loan makes the commons grow instead of
+shrinking it.
 
 ## Where it stands and how to help