Merge pull request #473 from transcom/amw-makefile-multi-branch-update

added documentation for new makefile command multi_branch

docs/getting-started/development/multiple-independent-branches.md

@@ -0,0 +1,12 @@
+# Multiple Independant Branches
+**Purpose**: To setup multiple local dev environments so that the developer can easily continue working with a branch while a process or operation is running on a separate project folder.
+
+**How to start**: From the current project folder, run the following command:
+```
+make multi_branch
+```
+**End result**: You should end up with 2 folders; each with their own instance of the MilMove git repository cloned down.
+Special considerations:
+- Once the command completes execution successfully, you should be able to run the local server from each instance simultaneously.
+- Currently no more than 2 instances of the MilMove project folder is supported at a time.
+- In the case that you already have a .envrc.local file set up, none of the file's contents should be changed except for the GIN_PORT assigned.