[feature] Set/show instance language(s); show post language on frontend (#2362)

* update go text, include text/display

* [feature] Set instance langs, show post lang on frontend

* go fmt

* WebGet

* set language for whole article, don't use FA icon

* mention instance languages + other optional config vars

* little tweak

* put languages in config properly

* warn log language parse

* change some naming around

* tidy up validate a bit

* lint

* rename LanguageTmpl in template

web/template/about.tmpl

@@ -25,6 +25,22 @@
 			{{.instance.Description |noescape}}
 		</div>
 
+		<div>
+			<h2 id="languages">Languages</h2>
+			<p>
+				{{ if .languages }}
+					This instance prefers the following languages:
+					<ol>
+						{{range .languages}}
+						<li>{{.}}</li>
+						{{end}}
+					</ol>
+				{{ else }}
+					This instance does not have any preferred languages. 
+				{{ end }}
+			</p>
+		</div>
+
 		<div>
 			<h2 id="contact">Admin Contact</h2>
 			{{if .instance.ContactAccount}}
@@ -81,7 +97,7 @@
 		<div>
 			<h2 id="moderated-servers">Moderated servers</h2>
 			<p>
-				ActivityPub instances exchange (federate) data with other servers, including accounts and toots.
+				ActivityPub instances exchange (federate) data with other instances, including accounts and toots.
 				This can be prevented for specific domains by suspending them. None of their content is stored,
 				and interaction with their users is blocked both ways.</br>
 				{{if .blocklistExposed}}