Remove unnecessary rss_icon line from _config.yml (alshedivat#3154)

Also make document clearer for rss_icon.

Author: CalaW

_config.yml

@@ -42,8 +42,6 @@ repo_trophies:
 # will use title and url fields
 # Take a look to https://github.com/jekyll/jekyll-feed for more customization
 
-rss_icon: true
-
 # -----------------------------------------------------------------------------
 # Layout
 # -----------------------------------------------------------------------------

_data/socials.yml

@@ -29,7 +29,7 @@ inspirehep_id: 1010907 # Inspire HEP author ID
 # publons_id: # your ID on Publons
 # quora_username: # your Quora username
 # research_gate_profile: # your profile on ResearchGate
-rss_icon: true # set to true to show the RSS icon
+rss_icon: true # comment this line to hide the RSS icon
 scholar_userid: qc6CJjYAAAAJ # your Google Scholar ID
 # scopus_id: # your profile on Scopus
 # semanticscholar_id: # your Semantic Scholar ID