Improved inline docs for set_transient & set_site_transient in options.php

[edwin-at-studiojoyo.com]

The maximal length for the string $transient is not defined in the inline documentation. This patch adds this for set_transient and set_site_transient.

In the Codex (#15058) there is already a discussion about this topic; however, that is about validation. And as this discussion is still ongoing, this addition to the inline documentation is helpful to the developers and users.

[DrewAPicture]

Is the 45 character limit a suggestion or a requirement? If it's a requirement, we should use "must" rather than "should".

[edwin-at-studiojoyo.com]

The maximal length is a requirement, as the transient name will fail if maximal length is exceeded. Thus, "should" must be changed to "must":

MUST: This word, or the terms "REQUIRED" or "SHALL", mean that the definition is an absolute requirement of the specification. (see ​http://www.ietf.org/rfc/rfc2119.txt).

Will attach newly corrected patch.

As an addition, the Codex (​http://codex.wordpress.org/Function_Reference/set_transient and ​http://codex.wordpress.org/Function_Reference/set_site_transient) must also use the word "must", in stead of "should".

[edwin-at-studiojoyo.com]

Changed 'should' to 'must'

[DrewAPicture]

In 28735:

Improve inline documention for set_transient() and set_site_transient() to specify the 45- and 40-character limits for their respective transient name values.

Props edwin-at-studiojoyo.com for the original patch.
See #15058, #13310. Fixes #28467.