docs: fix broken nemo-gym Core Components link

The link in nemo-gym-integration.md pointed at
docs.nvidia.com/nemo/gym/latest/about/concepts/core-components.html
which returns 404. The page is actually served at
docs.nvidia.com/nemo/gym/about/core-components (no /latest/, no
/concepts/) per the gym docs sitemap.

Update the source link instead of suppressing it via the linkcheck
false-positives walkaround.

Signed-off-by: Zhiyu Li <zhiyul@NVIDIA.com>

Author: ZhiyuLi-Nvidia

docs/design-docs/nemo-gym-integration.md

@@ -181,7 +181,7 @@ sequenceDiagram
     GRPO->>Policy: Compute loss and train
 ```
 
-> **NeMo Gym server types** (see [Core Components](https://docs.nvidia.com/nemo/gym/latest/about/concepts/core-components.html)):
+> **NeMo Gym server types** (see [Core Components](https://docs.nvidia.com/nemo/gym/about/core-components)):
 > - **Agent Server**: Orchestrates the rollout loop
 > - **Model Server**: HTTP proxy to vLLM; translates Responses API ↔ Chat Completions
 > - **Resource Server**: Provides tools and rewards