Fix mdbook-spec identifiers to be unique

Author: chorman0773

src/expressions/loop-expr.md

@@ -1,6 +1,6 @@
 # Loops and other breakable expressions
 
-r[expr.block]
+r[expr.loop]
 
 r[expr.loop.syntax]
 > **<sup>Syntax</sup>**\
@@ -32,7 +32,7 @@ Rust supports five loop expressions:
 r[expr.loop.break-label]
 All five types of loop support [`break` expressions](#break-expressions), and [labels](#loop-labels).
 
-r[expr.loop.continue]
+r[expr.loop.continue-label]
 All except labelled block expressions support [`continue` expressions](#continue-expressions).
 
 r[expr.loop.explicit-result]

src/expressions/operator-expr.md

@@ -305,7 +305,7 @@ r[expr.arith-logic.syntax]
 > &nbsp;&nbsp; | [_Expression_] `<<` [_Expression_]\
 > &nbsp;&nbsp; | [_Expression_] `>>` [_Expression_]
 
-r[expr.arith-logic.syntax]
+r[expr.arith-logic.intro]
 Binary operators expressions are all written with infix notation.
 
 r[expr.arith-logic.behavior]

src/expressions/tuple-expr.md

@@ -4,8 +4,6 @@ r[expr.tuple]
 
 ## Tuple expressions
 
-r[expr.tuple]
-
 r[expr.tuple.syntax]
 > **<sup>Syntax</sup>**\
 > _TupleExpression_ :\