app-misc/cheat: shell-completion, several fixes

- Now making use of the 'shell-completion' eclass
- Removed 'zsh-completion' USE flag (completion is now installed
  undonditionally)
- No longer building manpage since it's pre-built in the release
- Therefore: No longer depending on app-text/pandoc at build time
- Removed weird total blocking of app-shells/zsh-completion. Now
  soft-blocking app-shells/zsh-completion < 0.34.0 because it used to
  install the zsh completion '_cheat' before 0.34.0.

Signed-off-by: Jonas Frei <freijon@pm.me>

app-misc/cheat/cheat-4.3.3-r1.ebuild

@@ -0,0 +1,43 @@
+# Copyright 2019-2023 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit go-module optfeature shell-completion
+
+DESCRIPTION="cheat allows you to create and view interactive cheatsheets on the command-line"
+HOMEPAGE="https://github.com/cheat/cheat"
+SRC_URI="https://github.com/${PN}/${PN}/archive/${PV}.tar.gz -> ${P}.tar.gz"
+
+# licenses present in the final built
+# software. Checked with dev-go/golicense
+LICENSE="MIT Apache-2.0 BSD BSD-2"
+SLOT="0"
+KEYWORDS="~amd64 ~x86"
+IUSE="man"
+
+RDEPEND="!<app-shells/zsh-completions-0.34.0"
+BDEPEND=""
+
+src_compile() {
+	ego build -o ${PN} ./cmd/${PN}
+}
+
+src_test() {
+	ego test ./cmd/${PN}
+}
+
+src_install() {
+	dobin ${PN}
+
+	use man && doman doc/${PN}.1
+
+	newbashcomp scripts/${PN}.bash ${PN}
+	dofishcomp scripts/${PN}.fish
+
+	newzshcomp scripts/${PN}.zsh _${PN}
+}
+
+pkg_postinst() {
+	optfeature "fzf integration" app-shells/fzf
+}