Update of comments in thermistor table files. No functional changes.

[ABH10]

There are a lot of mistakes in the comments for various thermistor tables. I checked all the bed thermistor tables (not Pt100 tables) and updated the comments.
One issue is reported here:
#8862

Table 8 is for 10k pull-up and beta_25 == 3950. Device name is NTCS0402E3104FHT, not NTCS0603E3104FXT.
Table 12 is for 4.7k pull-up and beta_25 == 4700K, not for beta_25 == 4100K
Table 13 is for 4.7k pull-up and beta_25 == 4700K, not for beta_25 == 3950K
Table 6 is supposed to be an alternative EPCOS linearization. Assuming that the "EPCOS" device has R25 == 100 kOhm and beta25 = 4092K, then the only pull-up that gives reasonable (but not very good) results is 8.2 kOhm. A 4.7kOhm pull-up cannot give reasonable results for any beta25 value.

It seems that some of these tables are results of peoples measurements, which doesn't make sense. The tables that are included in Marlin should correspond to nominal values of thermistor parameters and nominal values of pull-up resistors. Nominal values, as given in datasheets for a particular NTC resistor are supposed to be the best general fit in average. People can make fine-tuned tables from measurements on their own devices and circuits, but such tables are not relevant in general.

[thinkyhead]

This is great, but needs to be targeted to the bugfix-1.1.x branch. Also, if you're up for it, we need to apply the same changes to bugfix-2.0.x, so we ask for a second PR targeted at that branch. Otherwise, I or another contributor will apply it to bugfix-2.0.x.