Adding to formatting notes

README.md

@@ -11,11 +11,15 @@ You can use this list one of two ways:
  - Overriding DNS for these hostnames to point to the IP of your cache server.
  - Use them in Squid with WCCP to redirect content to the right cache server.
 
-There is a separate file for each caching service. Some notes on formatting:
+There is a separate file for each cacheable service. Some notes on formatting:
 
   - Every line should be a seperate hostname for that service.
-  - Wildcards can be represented with a space.
+  - Wildcards can be represented with an asterix.
+  - Only one wildcard is permitted per line.
+  - If a wildcard is used, it should be the first character on the line.
+  - Wildcards are not treated as matching null, e.g. `*.example.com` will match `a.example.com` but will not match `example.com`
   - Lines starting with a # will be treated as a comment.
+  - Files must end with an empty newline.
 
 ## Updates
 
@@ -47,4 +51,4 @@ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+SOFTWARE.