Fix typo in build-ref.html
Closes
@@ -183,7 +183,7 @@ src/my/app/tests/test.cc
The second part of the label is the un-qualified package name
<code>my/app/main</code>, the path to the package
relative to the repository root. Together, the repository name and the
- un-qualfied package name form the fully-qualified package name
+ un-qualified package name form the fully-qualified package name
<code>@myrepo//my/app/main</code>. When the label refers to the same
package it is used in, the package name (and optionally, the colon)
may be omitted. So, inside <code>@myrepo//my/app/main</code>,
