docs: update README and data/README for expanded dataset and new layout

- README.md: refresh dataset summary numbers and link to expanded
  manufacturer coverage
- data/README.md: document the brand/<country>/ + cpu/<mfr>/<year>/<segment-group>/
  conventions and the new categories list

Refs #1

Author: Seungpyo1007

README.md

@@ -106,7 +106,7 @@ Data is organised by category and brand with singular folder names. It is a
 data/brand/<slug>.json                       # e.g. data/brand/samsung.json
 data/soc/<manufacturer>/<slug>.json           # data/soc/qualcomm/snapdragon-8-elite.json
 data/smartphone/<brand>/<slug>.json           # data/smartphone/samsung/galaxy-s25.json
-data/gpu/<manufacturer>/<slug>.json           # data/gpu/nvidia/geforce-rtx-5090.json
+data/gpu/<manufacturer>/<year>/<segment>/<slug>.json  # data/gpu/nvidia/2025/consumer/geforce-rtx-5090.json (split by year then consumer/enterprise)
 data/cpu/<manufacturer>/<year>/<slug>.json    # data/cpu/intel/2023/core-i9-14900k.json (CPU also by year)
 ```
 

data/README.md

@@ -7,10 +7,14 @@ singular folder names, organised by brand:
 brand/<slug>.json
 soc/<manufacturer>/<slug>.json
 smartphone/<brand>/<slug>.json
-gpu/<manufacturer>/<slug>.json
-cpu/<manufacturer>/<year>/<slug>.json   # CPUs are additionally split by release year
+gpu/<manufacturer>/<year>/<segment>/<slug>.json   # GPUs are split by release year then segment (consumer | enterprise)
+cpu/<manufacturer>/<year>/<slug>.json             # CPUs are additionally split by release year
 ```
 
+GPU `<segment>` is:
+* `consumer` — gaming/desktop & laptop dGPUs (GeForce GTX/RTX, Radeon RX/R9/HD, Arc, Voodoo, MTT S60/S70/S80, …)
+* `enterprise` — datacenter compute, AI accelerators, workstation pro cards (Tesla, A100/H100/B200, Quadro/RTX A/RTX PRO, Radeon Pro W, Instinct MI, MTT S3000/S4000, Vega Frontier, AI-focused TITAN V/RTX, …)
+
 > ⚠️ **This is a curated subset — NOT an exhaustive list of every device/chip.**
 > It is hand-verified and intentionally partial. Breadth is expanded out-of-band
 > through an internal pipeline that publishes curated records here after review;