Add example of .valid-feedback, .valid-tooltip and .invalid-tooltip

[ysds]

The example of .valid-feedback, .valid-tooltip and .invalid-tooltip does not seem to be in the document. Should we add these examples? especially it would be useful to clarify how to use invalid/valid-tooltip. Thanks.

Related SCSS:

bootstrap/scss/mixins/_forms.scss

Lines 31 to 51 in 8df34b0

	.#{$state}-feedback {
	display: none;
	margin-top: $form-feedback-margin-top;
	font-size: $form-feedback-font-size;
	color: $color;
	}
	.#{$state}-tooltip {
	position: absolute;
	top: 100%;
	z-index: 5;
	display: none;
	width: 250px;
	padding: .5rem;
	margin-top: .1rem;
	font-size: .875rem;
	line-height: 1;
	color: #fff;
	background-color: rgba($color, .8);
	border-radius: .2rem;
	}

[tmorehouse]

.valid-feedbck works nicely, although not sure about invalid or valid tooltip. It appears to make a fixed width (250px) red or green background behind the tooltip, rather than changing the tooltip background color.