feat(SEO): Add header and documentation for Claiming Website on Yandex

Signed-off-by: Pablo Iranzo Gómez <Pablo.Iranzo@gmail.com>

Author: iranzo

documentation/content/Analytics SEO SMO/claim-site.md

@@ -1,6 +1,6 @@
 ---
-Title: Claim website on Google and Bing
-Tags: google, bing, crawler
+Title: Claim website on Google, Yandex and Bing
+Tags: google, bing, yandex, crawler
 Category: Analytics, SEO and SMO
 Date: 2019-06-27
 Slug: website-claim
@@ -10,8 +10,7 @@ Summary: Easily insert headers to claim website
 Keywords:
 ---
 
-For submitting a website and sitemap to Google Search Console or Bing Webmaster tools
-we've to consider some steps.
+For submitting a website and sitemap to Google Search Console or Bing Webmaster tools or Yandex Webmaster we've to consider some steps.
 
 One of those steps is to claim the website ownership.
 
@@ -33,11 +32,13 @@ headers:
 
 - `CLAIM_GOOGLE`
 - `CLAIM_BING`
+- `CLAIM_YANDEX`
 
 Each one of those should be filled according to the values provided by
 Google/Bing on their respective websites for webmasters:
 
 - [Google Search Console](https://www.google.com/webmasters/tools/dashboard?pli=1)
 - [Bing Webmaster tools](https://www.bing.com/webmaster/configure/verify/ownership)
+- [Yandex Webmaster](https://webmaster.yandex.com/sites/)
 
 Once configured and when site is regenerated, the header should be there.

templates/_includes/claim_yandex.html

@@ -0,0 +1 @@
+        <meta name="yandex-verification" content="{{ CLAIM_YANDEX }}" />

templates/base.html

@@ -9,7 +9,9 @@
         {% endif %}
         {% if CLAIM_BING %}
         {% include '_includes/claim_bing.html' with context %}
-
+        {% endif %}
+        {% if CLAIM_YANDEX %}
+        {% include '_includes/claim_yandex.html' with context %}
         {% endif %}
         {% if article and article.author %}
         <meta name="author" content="{{ article.author }}" />