docs: Improve consistency and fix errors in README.md (#2107)

* docs: replace in-line links with reference links

* docs: add new reference links for a few terms

* docs: consistent use of "check if the string"

* docs: fix typo -> locals to locales

* docs: consistently end sentences with a dot

* docs: consistently wrap "options" with backticks

* docs: avoid contractions like it's or that's

* docs: avoid contractions like it's or that's (missed one)

* docs: fix typo - missing 's' in 'determines'

* docs: smaller improvements to isEmail

* correctly capitalize Gmail
* consistently use email
* fix grammatical error

* docs: consistently use space for option objects examples

* docs: isCreditCard - format to same style as rest

* renamed parameter from "card" to "str" to stay in line with all the other validators
* formatted valid values as array, in line with all other validators

* docs: isDate -format to same style as rest of validators

* renamed parameter "input" to "str"
* replaced "input" with "string" -> makes it clear that it only allows strings and does not work with Date objects

* docs: add missing dot(s) in 'e.g.'

* docs: consistently use space for option objects examples (missed one)

* docs: isStrongPassword slightly reword description

* stay consistent with wording of the other validators

* docs: consistently format option properties

* docs: isEthereumAddress - remove superfluous regex mention

Does not really add any additional useful information.
Most of these validators use RegExp as well

* docs: consistently use space for option objects examples (missed another one)

* docs: Sanitizers - use infinitve form, same as the rest

* docs: consistently list those locales/countryCodes arrays

* docs: consistently use "set to  bool"

* docs: fix isLicensePlate description

* locale is actually not optional currently. the function expects a string that is either literally 'any' or one of the supported locales
* format description consistently with the others validators

* docs: consistently format `'any'``

when first mentioned as option enclose it with backticks

* docs: correct use of a/an

* while URL starts with a vowel, so you would expect it to have "an", it is not the case, because it starts with a "you" sound

https://owl.purdue.edu/owl/general_writing/grammar/articles_a_versus_an.html

* docs: isIMEI - format option property w/ backticks

* docs: remove uneeded spaces

* docs: isWhitelisted - clearer description of what it does

* docs: fix isSlug doc

* added missing str parameter
* removed second part of the description -> the function does not support any `Options` or anything that allows to changy any behaviour - not sure why it was added there, but it has been there since the whole isSlug validator was added

* docs: isVAT - consistentcy, use 'check if the string'

* docs: normalizeEmail - improve consistency of terms and style

* consistently use Gmail
* infinitive form `canonicalizes` to `canonicalize``

* docs: consistently format and capitalize `locale`, when referring to it as a parameter.

in reference to #2107 (review)

* docs: fix missing commas and use consistent spacing

* docs: alphabetically order isMobilePhone locales

* docs: isTime - change wording to style of the other validators

* docs: alphabetically order isVAT countryCodes

* docs: alphabetically order isHash algorithms

Author: pano9000