Revert change in label_join per @RichiH

Signed-off-by: smedbergM <matthew.smedberg@gmail.com>

docs/querying/functions.md

@@ -272,7 +272,7 @@ For each timeseries in `v`, `label_join(v instant-vector, dst_label string, sepa
 using `separator` and returns the timeseries with the label `dst_label` containing the joined value.
 There can be any number of `src_labels` in this function.
 
-This example will return a vector with each time series having a `foo` label added to it, with the value `a,b,c`:
+This example will return a vector with each time series having a `foo` label with the value `a,b,c` added to it:
 
 ```
 label_join(up{job="api-server",src1="a",src2="b",src3="c"}, "foo", ",", "src1", "src2", "src3")