* Doc fixes and restructuring
This commit includes several misc changes to doc set. Create appendix
directory and add freq section with website images. Expand how-to
contribute section. Add reference to new 29 Host LAN mode. Add SNR sound
control to SNR graphs section. Add Radio Mobile Settings to How-To
section. Update images in Freq Spectrum section, and minimize reference
to "unshared" channels. Move Server Sync section to Services Overview.
* Fix misleading keyword search wording
Fix the misleading wording about doing a keyword search for AREDN.
* Fix total bandwidth allocation wording
Fix total bandwidth allocation wording in Radio Spectrum section.
* Clarify channel width at band edges
Clarify the warning against using wide channels that could transmit
outside of allowed FCC allocations.
* Heading change in services overview
* Add balancing comment about reducing channel width
Add a balancing comment that reducing channel width to increase SNR also
cuts throughput in half.
* Add SNR warning comment
* Fix reference to OpenWRT in screenshot
Replace reference to OpenWRT in screenshot with the AREDN login banner.
Add build files to gitignore. Change admonition type to attention. Create AREDN Services Guide and Services Overview docs as a work in progress. Update conf.py with new copyright year and release info. Expand index.rst with description of sections, and added Services Guide to toctree.
Steve Lewis KC0EUW