Typo fix: o -> To

[blegat]

This is consistent to what's writtin for 9 other variants:

➜  docs git:(master) grep -r " o obtain"
docs/variants/msi_z790/releases.md:This is a Dasharo Pro Package Release. o obtain access to the pre-built binaries,
docs/variants/msi_z690/releases.md:This is a Dasharo Pro Package Release. o obtain access to the pre-built binaries,
docs/variants/pc_engines/releases_seabios.md:This is a Dasharo Pro Package Release. o obtain access to the pre-built binaries,
docs/variants/pc_engines/releases_uefi.md:This is a Dasharo Pro Package Release. o obtain access to the pre-built binaries,
docs/variants/hardkernel_odroid_h4/releases.md:This is a Dasharo Pro Package Release. o obtain access to the pre-built binaries,
➜  docs git:(master) cd docs/variants 
➜  variants git:(master) grep -r " To obtain"
msi_z790/releases.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
novacustom_v540tu/releases_heads.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
novacustom_v560tu/releases_heads.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
dell_optiplex/releases.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
msi_z690/releases_heads.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
msi_z690/releases.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
msi_z690/releases.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
pc_engines/releases_seabios.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built
novacustom_nv4x_adl/releases_heads.md:This is a Dasharo Pro Package Release. To obtain access to the pre-built

[pietrushnic]

@blegat thanks. @artur-rs, let's resolve these linkChecker issues.