=doc #15160 Minor spelling, wording and grammar fixes.

1. Instance was incorrectly spelled as 'inctance'.
1. Improper use of between as the author is speaking of more than two routers (three in this case).
1. Replaced "routee actors" with "routees" to improve consistency with the remainder of the section.
1. Changed "10 nodes" to "10-node". The hyphenation is due to 10-node being a compound modifier for the word cluster. The word "node" was also changed to the singular.
1. On line 417, changed "coordinate" to "coordinates" as the latter is the singular form of the verb.
1. Added a couple of commas for subordinate clauses.