Remove obsolete staging info

Author: earlephilhower

doc/installing.rst

@@ -28,11 +28,6 @@ Instructions
 -  Don't forget to select your ESP8266 board from Tools > Board menu
    after installation.
 
-You may optionally use *staging* boards manager package link:
-``https://arduino.esp8266.com/staging/package_esp8266com_index.json``.
-This may contain some new features, but at the same time, some things
-might be broken.
-
 For more information on the Arduino Board Manager, see:
 
 - https://www.arduino.cc/en/guide/cores

tools/elf2bin.py

@@ -16,7 +16,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 import argparse
 import re

tools/platformio-build.py

@@ -4,7 +4,7 @@
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
 #
-#    http://www.apache.org/licenses/LICENSE-2.0
+#    https://www.apache.org/licenses/LICENSE-2.0
 #
 # Unless required by applicable law or agreed to in writing, software
 # distributed under the License is distributed on an "AS IS" BASIS,
@@ -19,7 +19,7 @@
 control devices attached to a wide range of Arduino boards to create all
 kinds of creative coding, interactive objects, spaces or physical experiences.
 
-http://arduino.cc/en/Reference/HomePage
+https://arduino.cc/en/Reference/HomePage
 """
 
 # Extends: https://github.com/platformio/platform-espressif8266/blob/develop/builder/main.py