Add instructions to udev rules file, and fix order (#230)

Adding the instructions is useful for linking to the file from elsewhere

Order fix supercedes #199

BUILDING.md

diff --git a/BUILDING.md b/BUILDING.md
index b71d9da..be0d849 100644
--- a/BUILDING.md
+++ b/BUILDING.md
@@ -30,7 +30,7 @@
 On Linux you can add udev rules in order to run picotool without sudo:
 
 ```console
-sudo cp udev/99-picotool.rules /etc/udev/rules.d/
+sudo cp udev/60-picotool.rules /etc/udev/rules.d/
 ```
 
 ### Windows

bazel/README.md

diff --git a/bazel/README.md b/bazel/README.md
index a1ad0f5..2dc7484 100644
--- a/bazel/README.md
+++ b/bazel/README.md
@@ -17,7 +17,7 @@
 On Linux you can add udev rules in order to run picotool without sudo:
 
 ```console
-sudo cp udev/99-picotool.rules /etc/udev/rules.d/
+sudo cp udev/60-picotool.rules /etc/udev/rules.d/
 ```
 
 ### macOS

udev/60-picotool.rules

diff --git a/udev/99-picotool.rules b/udev/60-picotool.rules
similarity index 84%
rename from udev/99-picotool.rules
rename to udev/60-picotool.rules
index 8459cec..846ffe0 100644
--- a/udev/99-picotool.rules
+++ b/udev/60-picotool.rules
@@ -1,3 +1,6 @@
+# Copy this file to /etc/udev/rules.d/
+# You can reload the udev rules with "udevadm control --reload"
+
 SUBSYSTEM=="usb", \
     ATTRS{idVendor}=="2e8a", \
     ATTRS{idProduct}=="0003", \