[css-position-3] Fix fatal link errors. Add 'Note:'.

Author: fantasai

css-position-3/Overview.bs

@@ -299,7 +299,7 @@ Containing Blocks of Positioned Boxes</h3>
 			The [=containing block=] is established by
 			the [=viewport=] in the case of [=continuous media=],
 			or the [=page area=] in the case of [=paged media=].
-			See [[#fixed-pos]].
+			See [[#fixpos-insets]].
 
 		<dt id="absolute-cb">If the box has ''position: absolute'':
 		<dd>
@@ -601,7 +601,7 @@ Sticky positioning</h3>
 	and the corresponding [=border edge=] of the box would be outside
 	the corresponding edge of the [=sticky viewport rectangle=],
 	then the box must be visually shifted
-	([[#relpos|as for relative positioning]])
+	([[#relpos-insets|as for relative positioning]])
 	to be inward of that [=sticky viewport rectangle=] edge,
 	insofar as it can while its [=position box=]
 	remains contained within its [=containing block=].
@@ -671,7 +671,7 @@ Absolute Positioning</h3>
 	that is the <dfn>weaker inset</dfn>;
 	otherwise the [=weaker inset=] is the end-edge inset.
 
-	Sizing and positioning of the [=absolutely positioned box=]
+	Note: Sizing and positioning of the [=absolutely positioned box=]
 	into this <dfn>inset-modified containing block</dfn>
 	is as described in [[#abspos-layout]].