releaser: Add release notes draft for 0.21
releaser: Add release notes draft for 0.21

* releaser: Add relase notes draft for release of 0.21

[ci skip]



fedelibre/hugo,anthonyfok/hugo,fedelibre/hugo,mitchchn/hugo,mdhender/hugo,digitalcraftsman/hugo,mdhender/hugo,mdhender/hugo,fedelibre/hugo,anthonyfok/hugo,gohugoio/hugo,fedelibre/hugo,mdhender/hugo,gohugoio/hugo,anthonyfok/hugo,digitalcraftsman/hugo,mitchchn/hugo,gohugoio/hugo