m78+: https://github.com/google/skia/blob/master/RELEASE_NOTES.txt (all the new changes have been listed in one file since m78)
m77: https://docs.google.com/document/d/1VARTQGtKY6FI57i0jQt-PMDMR-5dD-3dTo0Pb9pJMHA
m76: https://docs.google.com/document/d/1s4WUHpPT9pLBCeX-syElhX6qLCHxlKmRlsisrL2uwI8
m75: https://docs.google.com/document/d/1Neq2NoJIbSqnMGx_SpNwIQj3H0M3uIr5wRMNPr1W3Qs
m74: https://docs.google.com/document/d/1EcchH9qF66zrIqEPM3G0-T5LhT_guPLD3e7KbaJ3hsg
m73: https://docs.google.com/document/d/1wonKZEvzKk131Im3moBRkutDuD_HY8q-hRxaYeO5OP4
m72: https://docs.google.com/document/d/1U1p9_6YEPDOhTgBM8JYUYMCGCOXsQ7qajVOylkv05-I
m71: https://docs.google.com/document/d/140TGyz8jHUBBQkWmdvqmxyf0OkE3UHPWO-T03Aj_p3E
m70: https://docs.google.com/document/d/1JpOj7aXHcRVZUP1kaA3EwbXNU4xKOS2pe5rjFCfxtg4
m69: https://docs.google.com/document/d/1xhuXPCPoi-XGUPKWeWbSAqMd6_Pac0tIFBpJyK90m7s
m68: https://docs.google.com/document/d/1PaHYs59ah2MV7MC7TGfdXoXNwMMd7RAC7L0YbWvcVXE
m67: https://docs.google.com/document/d/1lRvgKWMxkLSn3H0UScALgjzm226XnCQPGZ-MDIuP-OQ
m66: https://docs.google.com/document/d/1xSMJHBXZZMftOXFaqK48gzgi9l6pbLOhHghXcvCD5j4
m65: https://docs.google.com/document/d/17reptjnrmJYE9Dmcx1ACVISCHd7REi3cXm-lYEsX7P0
m64: https://docs.google.com/document/d/1iz5wovguHH2KtUBXUOXXLXvJxjDxkS6KpDODKJF4_uY
m63: https://docs.google.com/document/d/1hxzL0Hc2ukfw8M7szWR_UDKvt2zdOsWvBv-2gxhbwoU
m62: https://docs.google.com/document/d/1D_NrR1c1_3JRZVHSPHaEx0KmmRotZ1HxeqO_HgCK9OI
m61: https://docs.google.com/document/d/1dVxPZN1zqW8c6gd4uF1TQlJ7EImMuWUXjYOuyaswztk
m60: https://docs.google.com/document/d/1lgU2rFPGV4WpZiynWCr7Ff_IA85nYyUTo0aG4Syatkc