Docs: suggesting smaller mixing parameters for non converging spin-polarized calculations

[Cstandardlib]

Linked Issue

Fix #7125

What's changed?

• Fix docs for mixing_beta & mixing_beta_mag to suggest smaller parameter values for scf hard to converge, as in BUG: USPP hard to converge and yields incorrect magnetic moments #7125.

Tests

Tests not required for now. A dedicated PR #7592 will be submitted to handle the docs & source consistency.

[Copilot]

Pull request overview

Updates ABACUS input-parameter documentation (and the corresponding built-in help text) to advise smaller/paired mixing parameters for hard-to-converge spin-polarized SCF calculations, in response to issue #7125.

Changes:

• Extend mixing_beta help text to recommend reducing mixing_beta and mixing_beta_mag together for difficult spin-polarized SCF.
• Extend mixing_beta_mag help text with the same paired-reduction guidance.
• Update docs/parameters.yaml mixing sections accordingly (but also includes multiple unrelated documentation changes beyond the stated PR scope).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 11 comments.

File	Description
source/source_io/module_parameter/read_input_item_elec_stru.cpp	Updates built-in parameter descriptions for mixing_beta and mixing_beta_mag.
docs/parameters.yaml	Updates parameter docs for mixing guidance and includes several additional documentation edits across other parameters.

[Cstandardlib]

Some PRs are making changes to docs without following the instructions after v3.9.0.24, so the documentation lags behind the source code.
And the agents do not allow the generate-parameters-yaml workflow now.

For example, #7384, #7354, #7280 update docs or add new params but did NOT update parameter.yaml, so the changes are not even present in input-main.md.

[QuantumMisaka]

My practices for mixing_beta tuning: 0.4 -> 0.1 -> 0.025 is a general way

[Cstandardlib]

Update docs to include advice by @QuantumMisaka.
Update input-main.
I note that input-main update is checked and required by agent governance but not by instructions.