Update dir-spec.txt to describe w line.
treedd42f1b740c6ead70b91c56ee014d7fb2c5fda11
-rw-r--r-- 2373 address-spec.txt
-rw-r--r-- 10905 bridges-spec.txt
-rw-r--r-- 19944 control-spec-v0.txt
-rw-r--r-- 76102 control-spec.txt
-rw-r--r-- 13200 dir-spec-v1.txt
-rw-r--r-- 41900 dir-spec-v2.txt
-rw-r--r-- 82239 dir-spec.txt
-rw-r--r-- 20245 path-spec.txt
drwxr-xr-x - proposals
-rw-r--r-- 34332 rend-spec.txt
-rw-r--r-- 3278 socks-extensions.txt
-rw-r--r-- 46300 tor-spec.txt
-rw-r--r-- 2147 version-spec.txt