Revise README for PixelTail S15 and update deployment documentation

[BillZhucn]

This pull request updates the documentation and workflow configuration for the PixelTail project. The main changes include clarifying the server cycle and whitelist process in the documentation, updating information about the current and permanent worlds, and making minor adjustments to the GitHub Actions workflow for building documentation.

Documentation updates:

• Updated the description in docs/seasons/README.md to clarify that PixelTail now alternates modded worlds with a permanent non-resetting vanilla world ("Neon"), extended the average duration of modded worlds to 6 months, and emphasized the use of the external login system.
• Updated the current world section to "PixelTail S15", added instructions for reapplying to the whitelist, and clarified that the current world is a 1.20.1 modded world.
• Moved the "Neon" world to a permanent world section and removed the redundant "其他周目" and "Neon" subsections at the end of the file.
• Reorganized the "过往周目" (Past Worlds) section and moved the S14 world into a comment for clarity.

Workflow configuration updates:

• Cleaned up the .github/workflows/Test_build.yml workflow by removing unnecessary comments and the line that creates a .nojekyll file after building docs. [1] [2] [3]

[Copilot]

Pull request overview

Updates PixelTail’s season/world documentation to reflect the new S15 cycle and clarifies whitelist/login expectations, alongside a small cleanup to the PR docs build workflow.

Changes:

• Revise docs/seasons/README.md to describe the “modded seasons + permanent vanilla (Neon)” model and update the “current world” to PixelTail S15 with re-whitelist guidance.
• Reorganize the “past worlds” section and remove redundant “other worlds/Neon” content now that Neon is a first-class “permanent world” section.
• Simplify .github/workflows/Test_build.yml by removing comments/blank lines and dropping the .nojekyll creation step.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
docs/seasons/README.md	Updates season/world narrative (S15 current + Neon permanent), plus section reorganization.
.github/workflows/Test_build.yml	Removes unnecessary lines from PR build workflow and drops .nojekyll creation.

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[Copilot]

这里的“请链接服务器”应为“请连接服务器”。

Suggested change

	本周目需要重新申请白名单，请链接服务器后看到 "You are not whitelisted on this server." 提示后，向管理员发送游戏id申请白名单！
	本周目需要重新申请白名单，请连接服务器后看到 "You are not whitelisted on this server." 提示后，向管理员发送游戏id申请白名单！