Reword jsx-no-bind rationale

[gpoole]

I'm proposing rewording the rationale for jsx-no-bind to:

• clarify that the performance concerns apply to specific situations; although it's qualified, the statement "is bad for performance" is a general statement and not strictly accurate
• refer explicitly to memo since I think memoised components are probably the most common component with performance impacts from this rule
• include the fact that this rule also covers any function declared in the render method of a component, including both anonymous or named functions, not just arrow or bound functions, as shown in the examples

[codecov]

Codecov Report

Merging #3581 (2b2a9bb) into master (7f655f8) will increase coverage by 0.00%.
The diff coverage is n/a.

❗ Current head 2b2a9bb differs from pull request most recent head ae64aa8. Consider uploading reports for the commit ae64aa8 to get more accurate results

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  Lines        9280     9295   +15     
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see 1 file with indirect coverage changes

[ljharb]

Thoughts on this?

Also, could we maybe add some examples as well to showcase the different kinds of functions that apply?

[gpoole]

I've also now updated the "when not to use section" to be consistent with the rationale. Sorry for the multiple micro edits!