It seems that the all the msc_inline_*.png files are missing from the SDK 6.1.0 documentation directory.
For example: file:///C:/Nordic%20Semiconductor/nRF51%20SDK_v6.1.0.0/Nordic/Documentation/s110/html/a00889.html Is missing: msc_inline_mscgraph_57.map msc_inline_mscgraph_57.png
The msc_inline_mscgraphs_*.png files are present in the v5.2.0 tree, for example: file:///C:/Nordic%20Semiconductor/nRF51%20SDK_v5.2.0.39364_Backup/Nordic/Documentation/html/a00842.html has: file:///C:/Nordic%20Semiconductor/nRF51%20SDK_v5.2.0.39364_Backup/Nordic/Documentation/html/msc_inline_mscgraph_1.png
As a sanity check I use msiextract to extact the files in nrf51_sdk_v6_1_0_b2ec2e6.msi and didn't find any msc_inline_* files, but I found 66 references to msc_inline_mscgraph_*.png files and 132 .map files.