Update Helm parameters table in installer/README.md to match all parameters used in templates

### What is the problem you're trying to solve The `installer/README.md` currently lists several Helm parameters, but this list is outdated. It does not include all the parameters actually supported and referenced inside our chart templates (e.g., `installer/helm/chart/volcano/templates/*.yaml`). Because the README and `values.yaml` sometimes fall out of sync with what the templates are actually parsing, users often get confused about which Helm parameters are available, what types they expect, and whether a parameter setting will actually take effect. ### Describe the solution you'd like I'd like to update the parameters table in `installer/README.md` to be a comprehensive source of truth. Specifically: 1. Audit and include every parameter actually used in the chart Go templates, not just those currently in `values.yaml`. 2. Use a clear table format that covers: - Parameter name - YAML path (for `values.yaml`) - Description - Type (e.g., int, string, bool) - Accepted values - Example 3. Remove or add deprecation notes for any parameters currently in the README that are no longer used by any templates. **Example Format:** | Parameter | YAML Path | Description | Type | Accepted Values | Example | |-----------------------------------|--------------------------------------------|---------------------------------------------|--------|-----------------|---------| | scheduler_percentage_nodes_to_find| custom.scheduler_percentage_nodes_to_find | Percentage of nodes scheduler checks | int | 0-100 | 10 | | ... | ... | ... | ... | ... | ... | ### Additional context If the parameter table grows too large for the README, we could alternatively move the full table to `docs/user-guide` and keep a summarized version or a link in the README. - [x] This feature requires design or user documentation changes.