Fix doc typos.

doc/_posts/2014-03-11-capnproto-0.4.1-bugfixes.md

@@ -8,7 +8,7 @@ Today I'm releasing [version 0.4.1 of Cap'n Proto](http://capnproto.org/capnprot
 As hinted by the version number, this is a bugfix and tweak release, with no big new features.
 
 You may be wondering:  If there are no big new features, what has been happening over the
-last three month?  Most of my time lately has been spent laying the groundwork for an
+last three months?  Most of my time lately has been spent laying the groundwork for an
 interesting project built on Cap'n Proto which should launch by the end of this month.
 Stay tuned!  And don't worry -- this new project is going to need many of the upcoming
 features on [the roadmap]({{ site.baseurl }}roadmap.html), so work on version 0.5 will be

doc/language.md

@@ -581,7 +581,7 @@ A protocol can be changed in the following ways without breaking backwards-compa
   encoding of any existing type.
 * New fields, enumerants, and methods may be added to structs, enums, and interfaces, respectively,
   as long as each new member's number is larger than all previous members.  Similarly, new fields
-  may be addded to existing groups and unions.
+  may be added to existing groups and unions.
 * New parameters may be added to a method.  The new parameters must be added to the end of the
   parameter list and must have default values.
 * Members can be re-arranged in the source code, so long as their numbers stay the same.

doc/rpc.md

@@ -212,7 +212,7 @@ features they have covered by advertising a level number.
 * **Level 4:**  Reference equality / joining.  If you receive a set of capabilities from different
   parties which should all point to the same underlying objects, you can verify securely that they
   in fact do.  This is subtle, but enables many security patterns that rely on one party being able
-  two verify that two or more other parties agree on something (imagine a digital escrow agent).
+  to verify that two or more other parties agree on something (imagine a digital escrow agent).
   See [E's page on equality](http://erights.org/elib/equality/index.html).
 
 ## Encryption