Fix logic error and make some settings optional in wg.conf template.

[nanhantianyi]

Fix logic error and make some settings optional in wg.conf template.

[ngoduykhanh]

Hey @nanhantianyi thanks for the PR. Could you please make your PR description more informative to speed up my PR review process? Which was the issue and why do we need some sitting optional in the config file template?
Please also always add an empty line at the end of the file. Thank you!

[nanhantianyi]

Hi @ngoduykhanh ,there is an {{end}} tag in wrong place which make the "Endpoint" config out of the range of ".Client.Enabled".
Make “PostUp”、”PreDown“、”PostDown“、”Table“ optional to ensure there is no empty config in generated file if user don't set them.

[ngoduykhanh]

Thanks for your clarification. It is a nice catch. I left 2 comments in your PR.