Typo (#83)

trivial typo correction.
diff --git a/site/src/site/asciidoc/index.adoc b/site/src/site/asciidoc/index.adoc
index f476551..a132afa 100644
--- a/site/src/site/asciidoc/index.adoc
+++ b/site/src/site/asciidoc/index.adoc
@@ -47,7 +47,7 @@
 The plural form of training was used frequently in the early stages of the project, which is strictly speaking not grammatically correct, as well as misleading from the perspective of this project.
 Training, being a gerund (verb used as noun) does not have a plural form, so should always be followed by a quantifiable noun like _sessions_ or _slides_.
 
-Additionally, the existence of this project is to a large extent based on the believe that a good training session consists of much more than just the material that is being shown, a distinction that is distracted from by the use of _training_ as all-encompassing term.
+Additionally, the existence of this project is to a large extent based on the belief that a good training session consists of much more than just the material that is being shown, a distinction that is distracted from by the use of _training_ as all-encompassing term.
 
 While we will not tell anybody how to phrase this, as a project we will try to keep any official wording as concise as possible and stay away from the use of _training_ or _trainings_.
 
@@ -70,4 +70,4 @@
 
 Wiki: https://cwiki.apache.org/confluence/display/TRAINING
 
-Jira: https://issues.apache.org/jira/browse/TRAINING
\ No newline at end of file
+Jira: https://issues.apache.org/jira/browse/TRAINING