Improve documentation and error messages for safe initialization

[liufengyun]

Improve documentation and error messages for safe initialization

[michelou]

@liufengyun Here are 3 more changes to Markdown file safe-initialization.md

Old	New
The three principles above	The four principles above
Another exception too this rule	Another exception to this rule
essentially invovles close	essentially involves close

[olhotak]

Otherwise LGTM.

[olhotak]

Suggested change

	In the `ThisRef` case, local reasoning ensures that all fields assigned implies that all fields themselves contain effectively hot values.
	In the `Warm` case, if the value `v` leaks outside the analysis scope, the unanalyzed code could instantiate inner classes of `v`, call methods on `v`, or read fields of `v`. The conditions of the `Warm` case ensure that these actions do not lead to accessing a cold object.
	In the `Fun` case, ...

[liufengyun]

Maybe we can add the justification later --- they are not immediately understandable to readers and can itself be an obstacle in reading the docs.

[liufengyun]

Apply suggested changes

[liufengyun]

Apply suggested changes

[liufengyun]

Thanks @michelou , I fixed two of them. Regarding

The three principles above

The usage of "three" is intended here and it's not a typo.