"Irradiance Transposition" documentation section ordering could be improved

[ramaroesilva]

Issue
The section ordering of Irradiance Transposition documentation in Example Gallery is not very fluid, in my opinion.

Current situation

1. Mixed Orientation
2. Reverse transposition using one year of hourly data
3. GHI to POA Transposition
4. Seasonal Tilt
5. Use different Perez coefficients with the ModelChain
6. Reverse transposition limitations
7. Modeling with interval averages
8. Modeling Transposition Gain

Proposal

1. GHI to POA Transposition
2. Modeling Transposition Gain
3. Modeling with interval averages (maybe could come before the one above)
4. Use different Perez coefficients with the ModelChain
5. Mixed Orientation
6. Seasonal Tilt
7. Reverse transposition using one year of hourly data6.
8. Reverse transposition limitations