add stackoverflow id (alshedivat#400)

Author: pourmand1376

_includes/social.html

@@ -12,11 +12,11 @@
 {% endif %}
 {%- if site.scholar_userid -%}
 <a href="https://scholar.google.com/citations?user={{ site.scholar_userid }}" title="Google Scholar"><i
-        class="ai ai-google-scholar"></i></a>
+                class="ai ai-google-scholar"></i></a>
 {% endif %}
 {%- if site.semanticscholar_id -%}
 <a href="https://www.semanticscholar.org/author/{{ site.semanticscholar_id }}" title="Semantic Scholar"><i
-        class="ai ai-semantic-scholar"></i></a>
+                class="ai ai-semantic-scholar"></i></a>
 {% endif %}
 {%- if site.publons_id -%}
 <a href="https://publons.com/a/{{ site.publons_id }}/" title="Publons"><i class="ai ai-publons"></i></a>
@@ -29,11 +29,11 @@
 {% endif %}
 {%- if site.research_gate_profile -%}
 <a href="https://www.researchgate.net/profile/{{site.research_gate_profile}}/" title="ResearchGate"><i
-        class="ai ai-researchgate"></i></a>
+                class="ai ai-researchgate"></i></a>
 {% endif %}
 {%- if site.scopus_id -%}
 <a href="https://www.scopus.com/authid/detail.uri?authorId={{site.scopus_id}}" title="Scopus"><i
-        class="ai ai-scopus"></i></a>
+                class="ai ai-scopus"></i></a>
 {% endif %}
 {%- if site.github_username -%}
 <a href="https://github.com/{{ site.github_username }}" title="GitHub"><i class="fab fa-github"></i></a>
@@ -64,7 +64,7 @@
 {% endif %}
 {%- if site.wikipedia_id -%}
 <a href="https://wikipedia.org/wiki/User:{{ site.wikipedia_id }}" title="Wikipedia"><i
-        class="fab fa-wikipedia-w"></i></a>
+                class="fab fa-wikipedia-w"></i></a>
 {% endif %}
 {%- if site.strava_userid -%}
 <a href="https://www.strava.com/athletes/{{ site.strava_userid }}" title="Strava"><i class="fab fa-strava"></i></a>
@@ -80,7 +80,7 @@
 {% endif %}
 {%- if site.stackoverflow_id -%}
 <a href="https://stackoverflow.com/users/{{ site.stackoverflow_id }}" title="Stackoverflow"><i
-        class="fab fa-stack-overflow"></i></a>
+                class="fab fa-stack-overflow"></i></a>
 {% endif %}
 {%- if site.kaggle_id -%}
 <a href="https://www.kaggle.com/{{ site.kaggle_id }}" title="Kaggle"><i class="fab fa-kaggle"></i></a>