doc: swap sides of equality in grind

[adomani]

The text below the example refers to the hypothesis p (q x) = 7 and to 7 as the "right-hand-side". The proposed order also satisfies the "LHS is more complicated than the RHS" heuristic.

[github-actions]

Preview for this PR is ready! 🎉 (also as a proofreading version). built with commit 5ca2ef1.

[adomani]

Actually, reading further, the following examples have the equality with 7 on the LHS. So,

• either, this change is the correct one and the later examples should similarly be modified;
• or, this change is incorrect and the text below this example should be adapted.

I do not know which alternative is correct, though!