installation: add missing td-agent-bit file

Signed-off-by: Eduardo Silva <[email protected]>

installation/td-agent-bit.md

@@ -0,0 +1,13 @@
+# TD-Agent Bit
+
+We distribute _Fluent Bit_ as packages for specific Enterprise Linux distributions under the name of __td-agent-bit__. These packages are maintained by
+[Treasure Data, Inc.](https://www.treasuredata.com).
+
+The following distributions are supported:
+
+| Distribution                 | Version | Codename     |
+|------------------------------|---------|--------------|
+| [Ubuntu](ubuntu.md)          | 16.04   | Xenial Xerus |
+| [Debian](debian.md)          |  8      | Jessie       |
+| [Raspbian](raspberry_pi.md)  |  8      | Jessie       |
+| [CentOS](redhat_centos.md)   |  7      |         |