docs: README examples no longer match v0.21.0's output

从 README.md 中引用的章节开始：第 1472–1525 行附近的示例、-V=full 的说明、格式错误指令表以及行号示例。在 commit 510cad4 上运行文档中列出的命令，并将输出与 README 的每个代码块进行比较。更新过时或不完整的示例和陈述，统一行号规范，并在可行时为 survey 和 inspect 代码块添加 golden test；当文档中的输出和陈述与命令一致时，即为完成。

These were checked by running the commands at 510cad4.

Example output

• "Silencing an unused report" (README.md:591-594): it runs plain declscope ./..., which is strict by default, but shows the loose wording nothing it reaches takes a scope. v0.21.0 prints …on B: it already has shared scope, and the same for T.F.

• Survey and inspect samples (README.md:1472-1525): several numbers are out of date, and rows are silently left out.

  Item	README	v0.21.0
  Survey declared	20	29
  markdown → cell mutual	empty	yes
  markdown → cell reached	7 of 10	7 of 18
  markdown → sink	5 of 17, 28 uses	5 of 18, 25 uses
  golden → (core)	4 of 78	4 of 79
  format → json	2 of 105	2 of 107
  Open declarations	114	109

  The survey sample leaves out the Packages — qualify table. The inspect sample drops rows such as json → summary from the middle of the table, and cuts the "Declarations crossed" sentence short.

Statements

• -V=full (README.md:227) says "A build from a checkout answers devel". go build in a checkout answers a VCS version. Only go run, or a build with -buildvcs=false, answers devel.

• The malformed-directive table (README.md:628-630) gives one directive's message for another:

  Input	README	Actual
  //declscope:core twice	duplicate declscope:namespace directive	duplicate declscope:core directive
  Two identical ignores	duplicate declscope:shared directive	duplicate declscope:ignore directive
  A stray //declscope:core	declscope:namespace must appear…	declscope:core must appear…

• Line numbers are counted two ways. Most examples treat the // file.go caption as outside the file (lines 114-115, 770-778, 1066 and 1159). The strict-fix example (534-537) and the account.go example (1100) count it as line 1.

Suggested fix

• Regenerate the samples, or mark them as excerpts.
• Use <name> in the message table.
• Pick one convention for line numbers.
• A golden test over the survey and inspect README blocks would keep them from drifting again.