docs: Improve consistency and fix errors in README.md

[pano9000]

Hello Team,

I have spent some time to go through the "Validators" section of the README.md and fix some typos, mistakes and general inconsistencies, e.g. inconsistent use of terms or formatting across these validators.

This also fixes two errors:

• 54cf4c9 fixes the isSlug description, which mentions something about an "option" which is not present in the code
• bd86f0b fixes the isLicensePlate description, which was hinting that the locale parameter is optional, while in fact the current code will throw an error (Uncaught Error: Invalid locale 'undefined'), if you try to run it without passing a locale as argument.

A lot of these changes can be seen as being nitpicking (which they are :-)), but I since I was at it, why not do it 100% properly :-)
I've tried to spread these changes in separate commits, so that you can cherry-pick if necessary

Kind regards,

Pano

Checklist

• PR contains only changes related; no stray files, etc.
• README updated (where applicable)
• Tests written (where applicable)

[codecov]

Codecov Report

Base: 100.00% // Head: 100.00% // No change to project coverage 👍

Coverage data is based on head (62cbf4a) compared to base (f97e8d4).
Patch has no changes to coverable lines.

Additional details and impacted files

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[WikiRik]

Nice work!

[braaar]

Suggested change

**isAlpha(str [, locale, options])** | check if the string contains only letters (a-zA-Z).<br/><br/>`Locale` is one of `['ar', 'ar-AE', 'ar-BH', 'ar-DZ', 'ar-EG', 'ar-IQ', 'ar-JO', 'ar-KW', 'ar-LB', 'ar-LY', 'ar-MA', 'ar-QA', 'ar-QM', 'ar-SA', 'ar-SD', 'ar-SY', 'ar-TN', 'ar-YE', 'bg-BG', 'bn', 'cs-CZ', 'da-DK', 'de-DE', 'el-GR', 'en-AU', 'en-GB', 'en-HK', 'en-IN', 'en-NZ', 'en-US', 'en-ZA', 'en-ZM', 'es-ES', 'fa-IR', 'fi-FI', 'fr-CA', 'fr-FR', 'he', 'hi-IN', 'hu-HU', 'it-IT', 'ko-KR', 'ja-JP', 'ku-IQ', 'nb-NO', 'nl-NL', 'nn-NO', 'pl-PL', 'pt-BR', 'pt-PT', 'ru-RU', 'si-LK', 'sl-SI', 'sk-SK', 'sr-RS', 'sr-RS@latin', 'sv-SE', 'tr-TR', 'uk-UA']` and defaults to `en-US`. Locale list is `validator.isAlphaLocales`. `options` is an optional object that can be supplied with the following key(s): `ignore` which can either be a String or RegExp of characters to be ignored e.g. " -" will ignore spaces and -'s.

**isAlpha(str [, locale, options])** | check if the string contains only letters (a-zA-Z).<br/><br/>`locale` is one of `['ar', 'ar-AE', 'ar-BH', 'ar-DZ', 'ar-EG', 'ar-IQ', 'ar-JO', 'ar-KW', 'ar-LB', 'ar-LY', 'ar-MA', 'ar-QA', 'ar-QM', 'ar-SA', 'ar-SD', 'ar-SY', 'ar-TN', 'ar-YE', 'bg-BG', 'bn', 'cs-CZ', 'da-DK', 'de-DE', 'el-GR', 'en-AU', 'en-GB', 'en-HK', 'en-IN', 'en-NZ', 'en-US', 'en-ZA', 'en-ZM', 'es-ES', 'fa-IR', 'fi-FI', 'fr-CA', 'fr-FR', 'he', 'hi-IN', 'hu-HU', 'it-IT', 'ko-KR', 'ja-JP', 'ku-IQ', 'nb-NO', 'nl-NL', 'nn-NO', 'pl-PL', 'pt-BR', 'pt-PT', 'ru-RU', 'si-LK', 'sl-SI', 'sk-SK', 'sr-RS', 'sr-RS@latin', 'sv-SE', 'tr-TR', 'uk-UA']` and defaults to `en-US`. Locale list is `validator.isAlphaLocales`. `options` is an optional object that can be supplied with the following key(s): `ignore` which can either be a String or RegExp of characters to be ignored e.g. " -" will ignore spaces and -'s.

If we are referring to the locale parameter, we should use the correctly cased name

[pano9000]

good catch, thank you!
will commit in a second

[WikiRik]

This looks good, but will cause some merge conflicts with other PRs so be cautious when merging this. @profnandaa

[profnandaa]

Sure, this is good work in the docs clean-up. Will surely cause some good number of merge conflicts. Let me handle this one as the last one before the next realease.

[pano9000]

I can also fix any possible merge conflicts here, if you let me know, when you are done with pulling in "feat" type commits for the upcoming release.