(Text from Minibuffer): Various corrections and clarifications.

(Text from Minibuffer): Various corrections and clarifications.
(Object from Minibuffer): Correct Lisp description of read-minibuffer.
(Minibuffer History): Clarify description of cons values for HISTORY arguments.
(Basic Completion): Various corrections and clarifications.
Add completion-regexp-list.
(Minibuffer Completion): Correct and clarify description of completing-read.
(Completion Commands): Mention partial-completion-mode.
Various other minor changes.
(High-Level Completion): Various corrections and clarifications.
(Reading File Names): Ditto.
(Minibuffer Misc): Ditto.