Small edits

[aarmey]

From reading through for other proofing:

• In Fig. 3, move over the legend so that it doesn't overlap with the schematic.
• Something happened to the colors in Fig. 4B
• Make the Fig. S7 time legend the same as in Fig. S5
• In Fig. 6, D/E/F should be on same row
• In Fig. 6, G/H/I/J should be on same row
• For the binding data, let's include the CD25 affinity measurements as Fig. S6, then just include the beta/gamma binding data as "Supplementary Data Table 1". Please check that the cytokine names are consistent in both of the new files, and that these are referenced in the text. After this is done I'll make one last pass though the whole paper, and send it off to coauthors for approval.