docs: Updated to include info on how to use git hook to validate code (#4484)

doc/Developing/Using-Git.md

@@ -62,6 +62,10 @@ git pull upstream master
 git push origin master
 ```
 
+At this stage it's worth pointing out that we have some standard checks that are performed when you submit a 
+pull request, you can run these checks [yourself](Validating-Code.md) to be sure no issues are present in your 
+pull request.
+
 Now, create a new branch to do you work on. It's important that you do this as you are then able to work on more than
 one feature at a time and submit them as pull requests individually. If you did all your work in the master branch then
 it gets a bit messy!

doc/Developing/Validating-Code.md

@@ -1,5 +1,7 @@
 source: Developing/Validating-Code.md
 
+#### Validating Code
+
 As part of the pull request process with GitHub we run some automated build tests to ensure that 
 the code is error free, standards [compliant](http://docs.librenms.org/Developing/Code-Guidelines/)
 and our test suite builds successfully.
@@ -26,3 +28,18 @@ Once composer is installed you can now run the code validation script:
 
 If you see `Tests ok, submit away :)` then all is well. If you see other output then it should contain 
 what you need to resolve the issues and re-test.
+
+#### Git Hooks
+
+Git has a hook system which you can use to trigger checks at various stages. Utilising the `pre-commit.php` 
+you can make this part of your commit process. You can do this in two ways:
+
+1. If you already make use of `.git/hooks/pre-commit` then you can add:
+
+./scripts/pre-commit.php
+
+to be excecuted when you run `git commit`.
+
+2. You can symlink the `pre-commit.php` file so it's executed directly on a `git commit`:
+
+`ln -s /opt/librenms/scripts/pre-commit.php /opt/librenms/.git/hooks/pre-commit`