Fix incorrectly-classified Protobuf files (#1094)

Alhadis · davelab6 · commit 7503f3c66297 · 2017-07-23T14:44:00.000-04:00
GitHub currently classifies this repository as a PureBasic codebase, due
to the abundance of METADATA.pb files. Setting "linguist-language" fixes
both the miscategorised files, and syntax highlighting missing from each
METADATA.pb file.
diff --git a/.gitattributes b/.gitattributes
@@ -0,0 +1 @@
+*.pb linguist-language=protobuf
