Documentation: base.yml comments don't match actual quantization option names in code

### Documentation

**URL or Section:**
- `src/MaxText/configs/base.yml` (lines 91-98)
- `src/MaxText/pyconfig.py` (line 287)
- `src/MaxText/layers/quantizations.py` (lines 642-692)
- `docs/explanations/quantization.md` (lines 51-56)

**Describe the problem:**

The inline comments in `base.yml` documenting the `quantization` config option contain **incorrect option names** that don't match the actual implementation in the codebase. This could cause users to use invalid configuration values.

**Issues found:**

1. **CRITICAL - Wrong option name**:
- `base.yml` documented `'nanoo_fp8'`
- Actual valid option in code: `'fp8_nanoo'` (see `pyconfig.py` line 287 and `quantizations.py` line 682)
- **Users following the comments would use an invalid option that doesn't exist!**

2. **Missing option**:
- `base.yml` did not mention `'fp8_gpu'`
- This option exists in `pyconfig.py` valid_quant_methods (line 287) and has implementation in `quantizations.py` (line 673)

3. **Misleading descriptions**:
- `base.yml` described `'fp8'` as "for 8-bit floating-point GeMMs on NVIDIA GPUs"
- But `'fp8_gpu'` is the actual NVIDIA-specific option
- `'fp8'` is the generic 8-bit floating-point quantization

4. **Inconsistency across documentation sources**:
- `pyconfig.py`: defines valid options as `("", "int8", "fp8", "fp8_full", "fp8_gpu", "fp8_nanoo")`
- `quantizations.py`: implements all these options in the case statement
- `quantization.md`: documents some of these options
- `base.yml`: had different names and missing options

**Expected behavior:**
The comments in `base.yml` should exactly match:
1. The valid option names defined in `pyconfig.py`
2. The case statements implemented in `quantizations.py`
3. The documentation in `quantization.md`

**Impact:**
- Users following the `base.yml` comments might try to use `'nanoo_fp8'` which would fail validation, causing confusion and errors
- Misleading description like "fp8 is for GPU" could cause users to incorrectly choose `'fp8'` when they specifically need GPU optimization (`'fp8_gpu'`), or vice versa, leading to suboptimal performance or unexpected behavior

### Additional Context

AI GDE / Kakao