Add GitHub inline macro with issue attribute

lib/asciidoctor/github-link-inline-macro/README.adoc

@@ -23,6 +23,10 @@ There are optional attributes for this macro.
 
 - `path` is the filepath to be linked within the repo.
 
+- `issue` accepts the issue number to be linked in the GitHub repo.
+Take note `issue` is exclusive to other attributes and has more precedence.
+For example, if `issue` and `rev` are both present, the link for issue will be the result.
+
 
 == Example usage
 
@@ -31,3 +35,7 @@ There are optional attributes for this macro.
 - `github:NixOS/nixpkgs[nixpkgs nixos-unstable branch, rev=nixos-unstable]` should link to the link:https://github.com/NixOS/nixpkgs/tree/nixos-unstable[NixOS unstable branch of nixpkgs] with a custom link text.
 
 - `github:errata-ai/vale[Vale v2.3.0 README, path=README.md, rev=v2.3.0]` should link to the link:https://github.com/errata-ai/vale/blob/v2.3.0/README.md[README of Vale v2.3.0].
+
+- `github:neovim/neovim[Neovim cannot open large files properly, issue=614]` should link to https://github.com/neovim/neovim/issues/614[an issue of Neovim].
+
+- `github:neovim/neovim[Neovim cannot open large files properly, issue=614, rev=master]` should still link to https://github.com/neovim/neovim/issues/614[an issue of Neovim] since `issue` has more precedence over `rev`.

lib/asciidoctor/github-link-inline-macro/extension.rb

@@ -14,8 +14,12 @@ class GitHubLinkInlineMacro < Asciidoctor::Extensions::InlineMacroProcessor
     text = attrs['caption'] || target
     uri = URI.parse %(https://github.com/#{target})
 
-    uri.path += %(/tree/#{attrs['rev']}) if attrs['rev']
-    uri.path += %(/#{attrs['path']}) if attrs['path']
+    if attrs.key? 'issue'
+      uri.path += %(/issues/#{attrs['issue']})
+    else
+      uri.path += %(/tree/#{attrs['rev']}) if attrs.key? 'rev'
+      uri.path += %(/#{attrs['path']}) if attrs.key? 'path'
+    end
 
     target = uri.to_s