Escape some code parts in manual.

This is needed to make the Markdown -> HTML conversion work with Pandoc, see jqlang#3183.

docs/content/manual/v1.7/manual.yml

@@ -999,15 +999,15 @@ sections:
 
           The key difference between `map(f)` and `map_values(f)` is
           that the former simply forms an array from all the values of
-          `($x|f)` for each value, $x, in the input array or object,
+          `($x|f)` for each value, `$x`, in the input array or object,
           but `map_values(f)` only uses `first($x|f)`.
 
           Specifically, for object inputs, `map_values(f)` constructs
           the output object by examining in turn the value of
-          `first(.[$k]|f)` for each key, $k, of the input.  If this
+          `first(.[$k]|f)` for each key, `$k`, of the input.  If this
           expression produces no values, then the corresponding key
           will be dropped; otherwise, the output object will have that
-          value at the key, $k.
+          value at the key, `$k`.
 
           Here are some examples to clarify the behavior of `map` and
           `map_values` when applied to arrays. These examples assume the
@@ -2239,13 +2239,13 @@ sections:
 
           jq provides a few SQL-style operators.
 
-          * INDEX(stream; index_expression):
+          * `INDEX(stream; index_expression)`:
 
             This builtin produces an object whose keys are computed by
             the given index expression applied to each value from the
             given stream.
 
-          * JOIN($idx; stream; idx_expr; join_expr):
+          * `JOIN($idx; stream; idx_expr; join_expr)`:
 
             This builtin joins the values from the given stream to the
             given index.  The index's keys are computed by applying the
@@ -2254,22 +2254,22 @@ sections:
             value from the index is fed to the given join expression to
             produce each result.
 
-          * JOIN($idx; stream; idx_expr):
+          * `JOIN($idx; stream; idx_expr)`:
 
             Same as `JOIN($idx; stream; idx_expr; .)`.
 
-          * JOIN($idx; idx_expr):
+          * `JOIN($idx; idx_expr)`:
 
             This builtin joins the input `.` to the given index, applying
             the given index expression to `.` to compute the index key.
             The join operation is as described above.
 
-          * IN(s):
+          * `IN(s)`:
 
             This builtin outputs `true` if `.` appears in the given
             stream, otherwise it outputs `false`.
 
-          * IN(source; s):
+          * `IN(source; s)`:
 
             This builtin outputs `true` if any value in the source stream
             appears in the second stream, otherwise it outputs `false`.
@@ -2789,7 +2789,7 @@ sections:
               {"title": "First post", "author": "Anonymous Coward"}
               {"title": "A well-written article", "author": "Person McPherson"}
 
-          We use a variable, $names, to store the realnames object, so that we
+          We use a variable, `$names`, to store the realnames object, so that we
           can refer to it later when looking up author usernames:
 
               .realnames as $names | .posts[] | {title, author: $names[.author]}