[nice to have] Some contributors / developers instructions

[fernflower]

It would be great to include some contributors guide / rtfm link with minimal information for people coming from outside of packer plugin development.
For example I'm currently struggling with the basics of "how do I build the plugin after I applied some changes to the source code so that packer picks it up" and would greatly benefit of anything like that.
Thanks!

[mkumatag]

Agree, lot needs to be improved.

[mkumatag]

if you want to modify and build/run then following make target can be used:

# Builds the code and installs the packer plugin code using packer command.
# Note: make sure to delete any pre-existing plugin in the machine - ref: https://developer.hashicorp.com/packer/docs/commands/plugins/remove
$ make install

[mkumatag]

uninstallation is also taken care part of the make target via #263 before installation

[fernflower]

Hmm actually the recent change has introduced some troubles with local install for me, so I had to revert it.
Looks like now it doesn't play nicely if the user removes the plugin manually.

ivasilev@ivasilev-thinkpadp1gen4i:~/projects/packer-plugin-powervs$ packer plugins remove github.com/ppc64le-cloud/powervs
/home/ivasilev/.packer.d/plugins/github.com/ppc64le-cloud/powervs/packer-plugin-powervs_v0.0.1-dev_x5.0_linux_amd64
ivasilev@ivasilev-thinkpadp1gen4i:~/projects/packer-plugin-powervs$ make install
No installed plugin found matching the plugin constraints github.com/ppc64le-cloud/powervs
make: *** [GNUmakefile:18: uninstall] Error 1
ivasilev@ivasilev-thinkpadp1gen4i:~/projects/packer-plugin-powervs$ packer plugins installed
/home/ivasilev/.packer.d/plugins/github.com/hashicorp/amazon/packer-plugin-amazon_v1.3.4_x5.0_linux_amd64
/home/ivasilev/.packer.d/plugins/github.com/hashicorp/ansible/packer-plugin-ansible_v1.1.2_x5.0_linux_amd64
/home/ivasilev/.packer.d/plugins/github.com/IBM/ibmcloud/packer-plugin-ibmcloud_v3.2.6_x5.0_linux_amd64

Revert:

ivasilev@ivasilev-thinkpadp1gen4i:~/projects/packer-plugin-powervs$ git diff
diff --git a/GNUmakefile b/GNUmakefile
index 94c0e61..c712d13 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -17,7 +17,7 @@ dev: build
 uninstall:
        @packer plugins remove github.com/ppc64le-cloud/powervs
 
-install: build uninstall
+install: build
        @packer plugins install -path ./${BINARY} "github.com/ppc64le-cloud/powervs"
 
 test:

[mkumatag]

Looks like now it doesn't play nicely if the user removes the plugin manually.

this can be ignored with - before the command