Edit release notes template and edit scripts (#981)

Making the release scripts easier to use as well as automating more of
the process.

make_release/release-note/gh-release-excerpt.nu

@@ -0,0 +1,42 @@
+#!/usr/bin/env nu
+
+
+# Prepare the GitHub release text
+def main [
+    versionname: string # The version we release now
+    bloglink: string # The link to the blogpost
+    date?: datetime  # the date of the last release (default to 3 weeks ago, excluded)
+] {
+    let date = (
+        if $date == null { (date now) - 4wk + 1day } else { $date }
+        | format date "%Y-%m-%d"
+    )
+
+    let repo = "nushell/nushell"
+    let query = $"merged:>($date)"
+
+    let prs = (
+        gh --repo $repo pr list
+            --state merged
+            --limit (inf | into int)
+            --json author,title,number,mergedAt,url
+            --search $query
+        | from json
+        | sort-by mergedAt --reverse
+        | update author { get login }
+    )
+
+    let authors = $prs.author | uniq | sort -i
+
+    let author_string = ($authors | each {|name| $"@($name)"} | str join ", " )
+
+    let release_text = [
+        $"This is the ($versionname) release of Nushell. You can learn more about this release here: ($bloglink)",
+        "",
+        "For convenience, we are providing full builds for Windows, Linux, and macOS. Be sure you have the requirements to enable all capabilities: https://www.nushell.sh/book/installation.html#dependencies", 
+        "",
+        $"This release was made possible by PR contributions from ($author_string)"
+    ]
+
+    $release_text | str join "\n"
+}