Improved pull request & clang-format instructions.

Change-Id: Ia439bcc61bac5788792244d10e573b1fba54b347

.github/PULL_REQUEST_TEMPLATE.md

 Thank you for submitting a PR!
 
-Please make sure you include the names of the affected language(s) in your PR title.
+Please delete this standard text once you've created your own description.
+
+Make sure you include the names of the affected language(s) in your PR title.
 This helps us get the correct maintainers to look at your issue.
 
 If you make changes to any of the code generators, be sure to run
@@ -11,6 +13,8 @@ If your PR includes C++ code, please adhere to the Google C++ Style Guide,
 and don't forget we try to support older compilers (e.g. VS2010, GCC 4.6.3),
 so only some C++11 support is available.
 
+For any C++ changes, please make sure to run `sh src/clang-format-git.sh`
+
 Include other details as appropriate.
 
 Thanks!

src/clang-format-all.sh

+# Running it twice corrects some bugs in clang-format.
+for run in {1..2}
+do
+  clang-format -i -style=file include/flatbuffers/* src/*.cpp tests/*.cpp samples/*.cpp grpc/src/compiler/schema_interface.h grpc/tests/*.cpp
+done
+git checkout include/flatbuffers/reflection_generated.h

src/clang-format-git.sh

+# Running it twice corrects some bugs in clang-format.
+for run in {1..2}
+do
+  git clang-format HEAD^ -- include/flatbuffers/* src/*.cpp tests/*.cpp samples/*.cpp grpc/src/compiler/schema_interface.h grpc/tests/*.cpp
+done
+git checkout include/flatbuffers/reflection_generated.h

src/clang-format.sh

-clang-format -i -style=file include/flatbuffers/* src/*.cpp tests/test.cpp samples/*.cpp grpc/src/compiler/schema_interface.h grpc/tests/*.cpp
-git checkout include/flatbuffers/reflection_generated.h