docs: update CSP section to mention Angular's minimum requirements (#43553)
docs: update CSP section to mention Angular's minimum requirements (#43553)

Closes angular/angular-cli#21711.
Refs #6361, #37631.

PR Close #43553

brandonroberts/angular,gkalpak/angular,angular/angular,brandonroberts/angular,gnomeontherun/angular,angular-indonesia/angular,angular-indonesia/angular,JiaLiPassion/angular,manekinekko/angular,JiaLiPassion/angular,angular-indonesia/angular,gnomeontherun/angular,ocombe/angular,shairez/angular,ocombe/angular,ocombe/angular,ocombe/angular,manekinekko/angular,angular/angular,gnomeontherun/angular,manekinekko/angular,manekinekko/angular,gkalpak/angular,shairez/angular,brandonroberts/angular,gkalpak/angular,angular/angular,shairez/angular,angular/angular,JiaLiPassion/angular,brandonroberts/angular,brandonroberts/angular,JiaLiPassion/angular,gnomeontherun/angular,manekinekko/angular,ocombe/angular,brandonroberts/angular,shairez/angular,manekinekko/angular,ocombe/angular,shairez/angular,gkalpak/angular,angular-indonesia/angular