ARROW-3350: [Website] Fix powered by links
Author: Amir Szekely <kichik@gmail.com>
Closes #2647 from kichik/patch-1 and squashes the following commits:
a122e5cf <Amir Szekely> Fix link & add PR link
diff --git a/powered_by.md b/powered_by.md
index a283bfe..f24f5b4 100644
--- a/powered_by.md
+++ b/powered_by.md
@@ -43,7 +43,7 @@
in descriptions is also always allowed, as in "BigCoProduct is a widget for
Apache Arrow".
-To add yourself to the list, please open a pull request adding your
+To add yourself to the list, please open a [pull request][27] adding your
organization name, URL, a list of which Arrow components you are using, and a
short description of your use case. See the following for some examples.
@@ -151,4 +151,5 @@
[23]: https://github.com/jpmorganchase/perspective
[24]: https://github.com/Paradigm4/accelerated_io_tools
[25]: https://github.com/uwdata/falcon
-[25]: https://fastdata.io/
+[26]: https://fastdata.io/
+[27]: https://github.com/apache/arrow/edit/master/site/powered_by.md
