fix a few "broken link" warnings (#20837)

compiler/concepts.nim

@@ -316,7 +316,7 @@ proc conceptMatch*(c: PContext; concpt, arg: PType; bindings: var TIdTable; invo
   ## concept's requirements. If so, we return true and fill the 'bindings' with pairs of
   ## (typeVar, instance) pairs. ('typeVar' is usually simply written as a generic 'T'.)
   ## 'invocation' can be nil for atomic concepts. For non-atomic concepts, it contains the
-  ## 'C[S, T]' parent type that we look for. We need this because we need to store bindings
+  ## `C[S, T]` parent type that we look for. We need this because we need to store bindings
   ## for 'S' and 'T' inside 'bindings' on a successful match. It is very important that
   ## we do not add any bindings at all on an unsuccessful match!
   var m = MatchCon(inferred: @[], potentialImplementation: arg)

compiler/ic/bitabs.nim

@@ -1,5 +1,5 @@
 ## A BiTable is a table that can be seen as an optimized pair
-## of (Table[LitId, Val], Table[Val, LitId]).
+## of `(Table[LitId, Val], Table[Val, LitId])`.
 
 import hashes, rodfiles
 

compiler/typeallowed.nim

@@ -8,7 +8,7 @@
 #
 
 ## This module contains 'typeAllowed' and friends which check
-## for invalid types like 'openArray[var int]'.
+## for invalid types like `openArray[var int]`.
 
 import
   intsets, ast, renderer, options, semdata, types