DOC: Fix a few typos

these are mostly spelling mistakes, some of them might be candidate for
backporting as well.
diff --git a/CONTRIBUTING b/CONTRIBUTING
index b5ba182..575e63b 100644
--- a/CONTRIBUTING
+++ b/CONTRIBUTING
@@ -309,7 +309,7 @@
    A good rule of thumb is that if your identifiers start to contain more than
    3 words or more than 15 characters, they can become confusing. For function
    names it's less important especially if these functions are rarely used or
-   are used in a complex context where it is important to differenciate between
+   are used in a complex context where it is important to differentiate between
    their multiple variants.
 
 9) Unified diff only
@@ -318,7 +318,7 @@
    that you have committed your patch to a local branch, with an appropriate
    subject line and a useful commit message explaining what the patch attempts
    to do. It is not strictly required to use git, but what is strictly required
-   is to have all these elements in the same mail, easily distinguishible, and
+   is to have all these elements in the same mail, easily distinguishable, and
    a patch in "diff -up" format (which is also the format used by Git). This
    means the "unified" diff format must be used exclusively, and with the
    function name printed in the diff header of each block. That significantly
@@ -773,7 +773,7 @@
 maintainers or authors of the modified files if their address appears at the
 top of the file.
 
-Please don't send pull-requests, they are really unconvenient. First, a pull
+Please don't send pull-requests, they are really inconvenient. First, a pull
 implies a merge operation and the code doesn't move fast enough to justify the
 use of merges. Second, pull requests are not easily commented on by the
 project's participants, contrary to e-mails where anyone is allowed to have an
diff --git a/include/types/connection.h b/include/types/connection.h
index 8a0ce79..3a7de64 100644
--- a/include/types/connection.h
+++ b/include/types/connection.h
@@ -56,7 +56,7 @@
 	int wait_reason;
 };
 
-/* A connection handle is how we differenciate two connections on the lower
+/* A connection handle is how we differentiate two connections on the lower
  * layers. It usually is a file descriptor but can be a connection id.
  */
 union conn_handle {