image: Fix bad HTML generation in code docs for cairo-format-stride-for-width

Patch from Simon Kågedal Reimer

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=63257
Add explanation to enum _cairo_int_status

Patch based on suggestion by Homer Hsing

Bugzilla:  https://bugs.freedesktop.org/show_bug.cgi?id=50416
Add explanation to _cairo_surface_create_in_error

Patch by Homer Hsing

Bugzilla:  https://bugs.freedesktop.org/show_bug.cgi?id=50413
Add comment to explain _cairo_edge_compute_intersection_*

Patch by Homer Hsing

Bugzilla:  https://bugs.freedesktop.org/show_bug.cgi?id=50412
Correct spelling of "tessellator" throughout code

Based on patch suggested by Homer Hsing

Bugzilla:  https://bugs.freedesktop.org/show_bug.cgi?id=50411