Add Kiswahili translation (#3489)

* Add Kiswahili translation

* Add Kiswahli to README

* Add Kiswahili to documentation

_data/ui-text.yml

@@ -1964,6 +1964,61 @@ ar-AE:
 ar-EG:
   <<: *DEFAULT_AR
 
+# Kiswahili
+# -----------------
+sw: &DEFAULT_SW
+  skip_links                 : "Ruka viungo"
+  skip_primary_nav           : "Ruka orodha kuu"
+  skip_content               : "Ruka maandiko maakuu"
+  skip_footer                : "Ruka chini"
+  page                       : "Ukurasa"
+  pagination_previous        : "Rudi"
+  pagination_next            : "Endelea"
+  breadcrumb_home_label      : "Ukurasa wa kwanza"
+  breadcrumb_separator       : "/"
+  menu_label                 : "Wezesha/Zima orodha"
+  search_label               : "Wezesha/Zima kutafuta"
+  toc_label                  : "Kwa ukurasa huu"
+  ext_link_label             : "Kiungo mbio"
+  less_than                  : "Soma kwa dakikia ndogo kuliko"
+  minute_read                : "Soma kwa dakika"
+  share_on_label             : "Tangaza"
+  meta_label                 :
+  tags_label                 : "Alama:"
+  categories_label           : "Aina:"
+  date_label                 : "Geuzi ya mwisho:"
+  comments_label             : "Wacha maoni"
+  comments_title             : "Maoni"
+  more_label                 : "Jifunze zaidi"
+  related_label              : "Pia, utapenda"
+  follow_label               : "Fuata:"
+  feed_label                 : "Feed"
+  powered_by                 : "Inatumia"
+  website_label              : "Tovuti"
+  email_label                : "Barua pepe"
+  recent_posts               : "Makala juzi"
+  undefined_wpm              : "Ingizo words_per_minute kwa _config.yml haijawekwa"
+  comment_form_info          : "Barua pepe yako haitaonekana. Kuna alama kwa ingizo tunahitaji."
+  comment_form_comment_label : "Maoni"
+  comment_form_md_info       : "Unaweza kutumia `Markdown`."
+  comment_form_name_label    : "Jina"
+  comment_form_email_label   : "Barua pepe"
+  comment_form_website_label : "Tovuti (hiari)"
+  comment_btn_submit         : "Tuma maoni"
+  comment_btn_submitted      : "Umetuma"
+  comment_success_msg        : "Asante kwa maoni yako! Itaonekana ikiridhiwa."
+  comment_error_msg          : "Pole, kuna makosa kwa ingizo yako. Tafadhali angalia umeandika kwa ingizo zote zinahitaji, na jaribu tena."
+  loading_label              : "Inapakiwa..."
+  search_label_text          : "Ingiza neno unatafuta..."
+  search_placeholder_text    : "Ingiza neno unatafuta..."
+  search_algolia_no_results  : "Hakuna matokeo"
+  results_found              : "Tumepata"
+  back_to_top                : "Rudi juu"
+sw-KE:
+  <<: *DEFAULT_SW
+sw-TZ:
+  <<: *DEFAULT_SW
+
 # Another locale
 # --------------
 #