Add missing by and to translations.

ui/src/components/post-listing.tsx

@@ -115,7 +115,7 @@ export class PostListing extends Component<PostListingProps, PostListingState> {
         <div className="details ml-4">
           <ul class="list-inline mb-0 text-muted small">
             <li className="list-inline-item">
-              <span>by </span>
+              <span>{i18n.t('by')} </span>
               <Link className="text-info" to={`/u/${post.creator_name}`}>{post.creator_name}</Link>
               {this.isMod && 
                 <span className="mx-1 badge badge-light"><T i18nKey="mod">#</T></span>
@@ -125,7 +125,7 @@ export class PostListing extends Component<PostListingProps, PostListingState> {
               }
               {this.props.showCommunity && 
                 <span>
-                  <span> to </span>
+                  <span> {i18n.t('to')} </span>
                   <Link to={`/c/${post.community_name}`}>{post.community_name}</Link>
                 </span>
               }

ui/src/translations/en.ts

@@ -128,6 +128,8 @@ export const en = {
     monero: 'Monero',
     code: 'Code',
     joined: 'Joined',
+    by: 'by',
+    to: 'to',
     powered_by: 'Powered by',
     landing_0: 'Lemmy is a <1>link aggregator</1> / reddit alternative, intended to work in the <2>fediverse</2>.<3></3>It\'s self-hostable, has live-updating comment threads, and is tiny (<4>~80kB</4>). Federation into the ActivityPub network is on the roadmap. <5></5>This is a <6>very early beta version</6>, and a lot of features are currently broken or missing. <7></7>Suggest new features or report bugs <8>here.</8><9></9>Made with <10>Rust</10>, <11>Actix</11>, <12>Inferno</12>, <13>Typescript</13>.',
     not_logged_in: 'Not logged in.',