Fix/remove carbon-proposals links (#267)

Co-authored-by: Matthew Riley <mdriley@gmail.com>

docs/design/metaprogramming.md

@@ -22,9 +22,8 @@ not be treated as accepted by the core team; rather, it is a placeholder until
 we have more time to examine this detail. Please feel welcome to rewrite and
 update as appropriate.
 
-See
-[carbon-proposals PR 89](https://github.com/carbon-language/carbon-proposals/pull/89)
-for context -- that proposal may replace this.
+See [proposal PR 89](https://github.com/carbon-language/carbon-lang/pull/89) for
+context -- that proposal may replace this.
 
 ## Overview
 

docs/design/operators.md

@@ -21,6 +21,5 @@ not be treated as accepted by the core team; rather, it is a placeholder until
 we have more time to examine this detail. Please feel welcome to rewrite and
 update as appropriate.
 
-See
-[carbon-proposals PR 5](https://github.com/carbon-language/carbon-proposals/pull/5)
+See [proposals PR 168](https://github.com/carbon-language/carbon-lang/pull/168)
 for context -- that proposal may replace this.