Add `.gitignore` for `tests` directory

.gitignore

@@ -23,8 +23,6 @@ bld/
 [Oo]bj/
 [Ll]og/
 ![Cc]ore/[Ll]og/
-tests/documentation/verify/
-tests/documentation/all.odin-doc
 # Visual Studio 2015 cache/options directory
 .vs/
 # Visual Studio Code options directory

tests/.gitignore

@@ -0,0 +1,19 @@
+# Ignore all files.
+*
+
+# Un-ignore all directories.
+!*/
+
+# Un-ignore files with an extension.
+#
+# In conjunction with the first two rules, this should catch extensionless
+# binaries on the UNIX-like platforms.
+!*.*
+
+# But remember to ignore executables with an extension.
+*.exe
+*.bin
+
+# Ignore documentation-related files.
+/documentation/verify/
+/documentation/all.odin-doc