small manual improvements

docs/concept.md

@@ -14,17 +14,17 @@ A single-player asymmetric game inspired by DOTA's wave/tower structure, combine
 ## Game World Layout (left to right)
 
 1. **Asteroid** — the player's factory and shipyards are built here. The HQ sits at the asteroid's right edge.
-2. **Player defence stations** — automatically engage approaching enemies; can be destroyed.
-3. **Enemy defence stations** — the push target; mark the right boundary of the scrollable area.
+2. **Player defence stations** — automatically engage approaching enemies; can be destroyed by the enemy.
+3. **Enemy defence stations** — the push target; can be destroyed by the player; mark the right boundary of the scrollable area.
 4. **Enemy spawn area** — waves originate from off-screen to the right.
 
 ## Factory & Belts
 
-- Factory buildings are placed from a queue and constructed one at a time, each taking some time to complete.
+- Factory buildings placed by the player are queued and constructed one at a time, each taking some time to complete.
 - The crafting/production tree is defined in a config file so it can be extended without code changes.
 - Materials are transported between buildings using belts (straight, curved) and splitters.
 - Buildings accept any material delivered by belts feeding into them; there are no labeled input ports. Each building has one fixed output port.
-- A building's input buffer holds up to twice the amount needed for one production cycle of the selected recipe.
+- Each building's input buffer can hold up to twice the amount needed for one production cycle of the selected recipe.
 
 ## Resources & Building Blocks