changes README's hello-world example for v3 (labstack#698)

* [doc] adding graceful documentation and example.

* adding myself to the maintainers list and minor comment formatting change

* [doc] updating code on the guides/context.md and guides/cookies.md to use v3 code.

* [doc] updating error-handling and request to v3 codebase

* [doc] updating templates documentation

* [doc] cleaning hello-world documentation for v3

* [content] adding website index content based on labstack#667

fixed labstack#697

Signed-off-by: Vishal Rana <vr@labstack.com>

Update README.md

Update JWT lib to v3

Signed-off-by: Vishal Rana <vr@labstack.com>

Updated gommon/log

Signed-off-by: Vishal Rana <vr@labstack.com>

Updated readme

Signed-off-by: Vishal Rana <vr@labstack.com>

Context#Form() > Context#FormValue(), Context#Query() > Context#Query…

…Param()

Signed-off-by: Vishal Rana <vr@labstack.com>